Description of the error codes Eberspacher parking heaters

Code	Description	Comments
000	No faults
001	Warning - overvoltage	Check vehicle charging system
002	Warning - undervoltage	Check batteries and connections
004	Warning - short in blower signal	*Airtronic: Check for short between pin 1 to blower relay. If no short exists replace control unit.
005	Warning - short circuit in anti-theft alarm output	*Hydronic II only. Not normally used, check wiring and connectors.
009	ADR / TRS - shut down (This can also be a spurious fault code)	a)ADR shutdown B1 pin 13 or 14. ADR is only used for vehicles carrying hazardous materials. b)Fault code 09 can also be generated after a heater is disconnected from power with the heater switch in the on position. A typical cause is disconnecting a plug after the heater has failed to start without turning off the switch on the controller. It can sometimes be erased by a diagnostic unit. Sometimes the code will not clear and a known fault needs to be introduced i.e. pull the fuel pump wires off and start the heater 5 times, this will move the fault to the end of the fault code memory and then it will be over written as the heater can only hold 5 faults. If that fails replace the ECU.
010	Overvoltage cut off	Voltage over 16 volts continuously for at least 20 seconds, (32 volt for 24 volt heaters). Check alternator regulator or disconnect battery charger. Possibly 12 volt heater connected to 24 volt battery but this could damage the ecu.
011	Undervoltage cut off (Low voltage at heater)	Voltage under 10.5 volts continuously for at least 20 seconds (21 volts for 24 volt heaters) IMPORTANT measure at the heater, not at the battery terminals where the voltage can be a lot higher. Usually occurs during starting when glowpin is on. Extremely common fault, usually due to a discharged battery but many other reasons described on our Low Voltage Faults page. The measurement method described in the Eberspacher Airtronic fault code list is almost useless, the heater must be connected and switched on so drawing current.
012	Overheating at overheat sensor (Software threshold value)	Temperature of the overheating sensor too high. Check heating air path for crushed pipes or blockages, air outlets closed or blocked. Often caused by accidentally puting objects against heating outlets. Check if air pipes are too long or have too many bends. (Just replacing a straight outlet hood with right angle version can often put the piping outside specification.) Check pumped fuel volume. Check Overheat sensor. Check blower fan as fault code 33. The heater can be reset from fault codes 012 and 013 by switching off and back on. Overheating is a serious safety issue and can damage the ECU so find and eliminate the cause before resetting. More info on our Faults Main page, mainly in the Faults when running section.
013	Overheating at flame sensor (Software threshold value)	*Airtronic Temperature of the flame sensor too high. Check as fault code 012. Check Flame sensor instead of overheat sensor.
014	Temperature difference between flame and overheat sensors too large	Temperature difference between flame and overheat sensors too large. Check as fault code 012. Check both Flame sensor and Overheat sensor.
015	Overheating lock out	This code displayed when the heater is switched on after fault code 017 was displayed. (I have no idea why this fault code is needed, code 017 covers the problem! On Hydronic water heaters the code is for 10 overheats in succession). More info in fault code 017.
016	Overheat - threshold temperature difference exceeded. (after FMP starts.) PLEASE NOTE! Fault code 016 is only displayed if the heater is running and the water temperature at the overheating sensor has reached at least 80 °C	Temperature values of the overheating sensor and the surface sensor is too large. For remedial action see Fault code 012. Check the surface sensor: – Check wiring for continuity, short circuit and damage. – Measure the resistance in connector B2 – between pin 7, (black) and pin 8, (black), see page 47 for measured values
017	Overheating lock out (Hardware limit value)	The temperature exceeded the maximum the overheat sensor can measure. The ECU is locked for safety reasons. The ECU failed to recognise overheating fault code 012 or 013. My explanation on why 017 occurs is on the Faults Main page. Heat may have damaged the ECU, if not it can be unlocked using appropriate equipment. IMPORTANT Identify and clear the cause of overheating before trying to reset. This lockout is for a very serious safety problem. More info on our Faults Main page. http://altox.ru/
018	Glow pin – start energy too low	Glow plug energy input is too low
019	Glow pin – ignition energy too low	*Hydronic II only. Energy input less than 2000 watts. Check Glowpin, Check ECU
020	Glowpin interruption (Glowpin open circuit)	Check for broken wires. Check glowpin resistance, 0.42 to 0.7 ohms, 24v glowpin 1.2 to 1.9 ohms. Measuring accurately is not required for fault code 020. For fault code 021 use accurate measurement technique shown on Faults Main page and Airtronic Servicing page 2.Manual gives alternative method but few users will have a suitable high current 8v supply. Eberspacher advise that connecting to a 12v battery might destroy the glowpin but so far our users report they had no problem while doing a short duration test on 12v. Make sure leads include a fuse when testing for 021 code. Caution, glowpin will glow red hot if working ok.
021	Glowpin drawing excessive current or short circuit downstream of earth	Check wiring for damage. Check for water leaking inside heater and on connectors. Check glowpin resistance as in code 020.
022	Glowpin drawing excessive current or short circuit downstream of +	*Hydronic II only. Check wiring for damage. Check for water leaking inside heater and on connectors.
023	Glowpin 2 interruption (Glowpin open circuit)	*Hydronic II with second glowpin only. Check as code 020
024	Glowpin 2 drawing excessive current or short circuit downstream of ground	*Hydronic II with second glowpin only. Check as code 021
025	Diagnostic line fault Heater remains operational	*Hydronic II only. This fault may prevent diagnostics equipment working as it uses the blue/white wire. Check blue/white diagnostic wire for damage or short circuit.
026	Glowpin 2 drawing excessive current or short circuit downstream of +	*Hydronic II with second glowpin only. Check as code 022
029	Glowpin 2 ignition energy too low	*Hydronic II with second glowpin only. Energy input less than 2000 watts. Check as code 019
030	Blower fan motor not rotating or rotating at wrong speed	* this code not used Hydronic II. Check fan is free to rotate and not catching on anything. Check wiring for breaks, loose connections, faulty insulation. Check combustion air path, both inlet and exhaust, are not obstructed. Blower brushes or bearings worn. If testing motor on a dc supply use 6 or 8v, not 12v.(Measurement as described in D4WSC D5WSC manual is completely wrong)
031	Blower fan motor interruption. (Open circuit)	Check wiring for breaks or loose connections. Check resistance of fan motor. Resistance should be approx 0.5 ohms, accuracy not critical for this test. Rotating shaft slowly by hand while checking may reveal faulty segments. If testing fan use 6 or 8v dc supply, not 12v.
032	Blower fan motor short circuit to earth or drawing excessive current.	Check wiring to blower for insulation damage. Check for water leaking inside heater and on connectors. Check motor is free to rotate and not catching on anything. Check bearings are not starting to seize. Check resistance of blower motor which should be approx 0.5 ohms. Use accurate measurement technique shown on Faults Main page and Airtronic Servicing page 2. Replace motor. If testing blower use 6 or 8v dc supply, not 12v. http://altox.ru/
033	Blower fan motor rotating at wrong speed	*Hydronic II only. Check as code 030
034	Blower fan motor short circuit downstream of + or -	*Hydronic II only. Check wiring to blower for insulation damage and touching other wiring. Check for water leaking inside heater and on connectors.
035	Reel partial load relay - interruption
036	Reel partial load relay - circuit
037	Water pump not working	*Hydronic II only. Check water pump Apply 12v to water pump, connector B1 pins 12 and 13 (Power input max 4 amps)
038	Relay for operating vehicle fan interruption (Open circuit) This fault is not displayed by all heater types.	* this code not used Hydronic II. Check wiring to relay for breaks or loose connection. Check relay: Disconnect 8 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 2 and 3. Depending upon type of relay a good reading should typically be around 80 ohms. If greater than 1000 ohms check relay coil resistance or replace relay.
039	Relay for operating vehicle fan short circuit, overload or short circuit to ground.	* this code not used Hydronic II. Check wiring to relay for insulation damage or broken connection touching. Check for water leaking inside heater and on connectors. Check relay: Remove relay, if fault 038 displayed replace relay. Alternative method: Disconnect 8 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 2 and 3. Depending upon type of relay a good reading should typically be around 80 ohms. If lower than 20 ohms remove relay. Then if resistance becomes very high replace relay.
040	Vehicle Blower - transistor error	Remove relay, if fault code 38 is displayed, the relay is defective.  Replace relay
041	Water pump interruption (Open circuit)	Check wiring to water pump for damage or breaks. Check resistance of the water pump, rotate shaft by hand while checking. Disconnect 14 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 10 and 11. No resistance figure is quoted but probably about 0.5 ohms. If trying pump on 12v battery without water keep test very short.
042	Water pump short circuit to earth or drawing excessive current	Check wiring to water pump for damage to insulation. Check for water leaking inside heater and on connectors. Check if pump is running dry. Vent heater, check header tank water level. Disconnect connection in water pump cable harness. If error code 041 is then shown replace water pump.
043	Water pump short circuit downstream of +	Check wiring to water pump for damage to insulation. Check for water leaking inside heater and on connectors.
047	Fuel metering pump short circuit to earth or overload current	Disconnect the wires on the pump connector, if fault code 048 is displayed pump is faulty. (If the pump has to be replaced please donate the faulty one to us for science.) If code 47 remains displayed check the wiring to the pump with a test meter for a short circuit. Most likely cause is mechanical damage to the insulation where cables are clipped in position or uninsulated connectors on older Eberspacher pump types touching the chassis. Check for water leaking inside heater and on connectors.
048	Fuel metering pump interruption (Open circuit)	Pump connector not fully pushed home or making a bad connection. Disconnect the wires on the pump connector and measure the resistance of the pump. The resistance of the pump should measure 10 ± 0.5 ohms (24v 36 ± 1.8 ohms). If not ok check connections for corrosion, replace pump. If pump is ok check wiring to pump. Measure resistance from connector. If no test meter is available the pump can be pulsed with a 12 volt battery. Connect and disconnect from the battery, each time it should make a loud click. (Make sure the pump wiring is not connected before doing this test or you can destroy the ECU. Also take care not to accidentally short circuit the battery). More info Fuel 2 page.
049	Fuel metering pump short circuit downstream of +	Check wiring to fuel pump for damage to insulation. Check for water leaking inside heater and on connectors.
050	Too many start attempts. ECU locked out	*Hydronic II - The ECU locks out after repeated start attempts without flame detection. Hydronic - The ECU locks out after 10 consecutive start attempt failures. Manual is not clear, I think a failed start with the second start attempt counts as one failure. IMPORTANT Identify and clear the cause before trying to reset. This lockout is for your safety as each attempt leaves unburnt fuel. It can be unlocked with appropriate equipment.
051	Flame detected during switch on (time exceeded blowing cold)	Flame sensor resistance above 1274 ohms at switch on indicates the temperature is above 70 degrees C and the fan runs to cool it down.If temperature does not fall below 70 degrees within aprox 4 minutes heater is switched off. Check flame sensor: Disconnect 14 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 1 and 2. If reading greater than 1274 ohms replace sensor.
052	Safety time exceeded. Unit failed to start on both start attempt sequences	No flame was detected during the two start attempt sequences, flame sensor value was below 80°C. Unit shut down after a cooling down cycle. This is simply a standard failure to start fault indication. Most heaters checked will have this code in memory, usually it can be ignored as you will already know when it failed to start, it switched off without generating any heat. The causes are detailed in Faults Main page.
053	Flame cutout in highest power stage	The flame extinguished during the boost / highest power stage. Fault code is deleted if automatic restart is ok. The causes are detailed in Faults Main page in the section "Eberspacher starts normally but stops whilst running, it may try to restart."
054	Flame cutout in high power, medium or medium 1, medium 2, medium 3, low power	The flame extinguished while operating. Power stage naming is different for some heaters. Fault deletion and causes same as fault 053. http://altox.ru/
055	Flame cutout in high power, medium or medium 1, medium 2, medium 3, low power	The flame extinguished while operating. Power stage naming is different for some heaters. Fault deletion and causes same as fault 053.
056	Flame cutout in high power, medium or medium 1, medium 2, medium 3, low power	The flame extinguished while operating. Power stage naming is different for some heaters. Fault deletion and causes same as fault 053.
057	Flame cutout in high power, medium or medium 1, medium 2, medium 3, low power	The flame extinguished while operating. Power stage naming is different for some heaters. Fault deletion and causes same as fault 053.
058	Flame cutout in high power, medium or medium 1, medium 2, medium 3, low power	The flame extinguished while operating. Power stage naming is different for some heaters. Fault deletion and causes same as fault 053.
059	*Hydronic II only. Too rapid rise in water temperature	Vent air from system. Open heater slide valve. Check water flow rate. Check temperature sensor. Resistance approx 0°C - 33000Ω, 20°C - 12450Ω, 50°C - 3600Ω, 100°C - 670Ω
060	Temperature sensor interruption (open circuit)	Check sensor wiring for damage or breaks. Check temperature sensor. Resistance approx 0°C - 33000Ω, 20°C - 12450Ω, 50°C - 3600Ω, 100°C 670Ω. Alternatively place short circuit across sensor (or connector pins for some models). If heater then shows error code 061 check and replace sensor. If 060 still appears replace ECU.
061	Temperature sensor short circuit, overload or short circuit to ground	Check wiring to temperature sensor for damage to insulation. Check for water leaking inside heater and on connectors. Check temperature sensor. Resistance approx 0°C - 33000Ω, 20°C - 12450Ω, 50°C - 3600Ω, 100°C - 670Ω. If resistance is much lower replace sensor.
062	Temperature control interruption (open circuit)	*Airtronic Heater received the switch on signal from the controller but could not read the controller temperature setting. Check grey/red wire for a break or loose connection. For a rheostat type controller only, disconnect S1 B1 and measure resistance between B1 pin 6 and pin 7, the control should adjust from 1750 to 2180 ± 80 ohms. If ok replace ECU, otherwise with B1 still disconnected measure across rheostat pins with grey/red and brown/white wires. If not ok replace controller. For more modern types of controller follow instructions on Faults Main page in section "Stage 2 Pre start failure".
063	Temperature control short circuit. Fault recognised only if it occurs in heating mode. If heater switched on with this fault ventilation mode is selected, (no fault code).	*Airtronic Detailed instructions on Faults Main page in section "Stage 2 Pre start failure". (The methods quoted in the manual will not work for some diagnostic equipment which need the controller on/off switch, eg the 801 controller.) Fault code indicates resistance value was less than 486 ohms.
064	Flame sensor interruption (open circuit)	Check sensor wiring for damage or breaks. Check Flame sensor: Resistance approx 0°C - 33000Ω, 20°C - 12450Ω, 50°C - 3600Ω, 100°C - 670Ω. If resistance is much higher replace sensor.
065	Flame sensor short circuit	Check sensor wiring for damage or breaks. Check Flame sensor: Resistance approx 0°C - 33000Ω, 20°C - 12450Ω, 50°C - 3600Ω, 100°C - 670Ω. If resistance is much higher replace sensor.
071	Overheat sensor interruption (open circuit)	Overheating sensor signals temperature value outside the measuring range. Check Overheat sensor resistance as fault code 012.Check sensor wiring for breaks and damage
072	Overheat sensor short circuit	Overheating sensor signals temperature value outside the measuring range. Check Overheat sensor resistance as fault code 012. Check sensor wiring for damage. http://altox.ru/
073	Overheating sensor recorded the fastest temperature rise
074	ECU defective	Overheating threshold detection hardware defective, ECU locked. Replace ECU
090	External interference voltage / External reset	ECU reset by external interference voltage. Check as code 099
091	Internal reset	ECU faulty
092	ROM error	ECU faulty
093	RAM error	ECU faulty
094	EEPROM error	Checksum error, ECU faulty
095	Invalid data record	Checksum error, ECU faulty
096	Internal temperature sensor faulty / ECU too hot	Internal temperature sensor faulty / ECU too hot, ECU faulty
097	Internal device errror	ECU faulty
098	Main relay is faulty	ECU faulty
099	Too many resets. Heater locked	Voltage short term drops below 5 - 6 volts (for 12 volt) or 7 - 8 volts (for 24 volt). Heater locked. This fault may damage the ECU. Check +12 volt and earth (0 volts) from the battery for loose or corroded connections. Check fuse and fuseholder, check battery terminals, check battery cables for damage. Check battery charger, especially Ctek chargers with too thin power output cables. Check battery condition. Leisure batteries, especially ones continuously float charged, can deteriorate with no other obvious signs unlike engine batteries which fail to start the engine so are quickly replaced. Simple voltage checks may still show ok even if battery is bad. Locate and clear cause before trying to reset, this fault may damage the ECU.
255	Erased memory device control unit

000

No faults

001

Warning - overvoltage

Check vehicle charging system

002

Warning - undervoltage

Check batteries and connections

004

Warning - short in blower signal

*Airtronic: Check for short between pin 1 to blower relay. If no short exists replace control unit.

005

Warning - short circuit in anti-theft alarm output

*Hydronic II only. Not normally used, check wiring and connectors.

009

ADR / TRS - shut down (This can also be a spurious fault code)

a)ADR shutdown B1 pin 13 or 14. ADR is only used for vehicles carrying hazardous materials.
b)Fault code 09 can also be generated after a heater is disconnected from power with the heater switch in the on position. A typical cause is disconnecting a plug after the heater has failed to start without turning off the switch on the controller.
It can sometimes be erased by a diagnostic unit. Sometimes the code will not clear and a known fault needs to be introduced i.e. pull the fuel pump wires off and start the heater 5 times, this will move the fault to the end of the fault code memory and then it will be over written as the heater can only hold 5 faults.
If that fails replace the ECU.

010

Overvoltage cut off

Voltage over 16 volts continuously for at least 20 seconds, (32 volt for 24 volt heaters). Check alternator regulator or disconnect battery charger. Possibly 12 volt heater connected to 24 volt battery but this could damage the ecu.

011

Undervoltage cut off (Low voltage at heater)

Voltage under 10.5 volts continuously for at least 20 seconds (21 volts for 24 volt heaters)
IMPORTANT measure at the heater, not at the battery terminals where the voltage can be a lot higher. Usually occurs during starting when glowpin is on.
Extremely common fault, usually due to a discharged battery but many other reasons described on our Low Voltage Faults page.
The measurement method described in the Eberspacher Airtronic fault code list is almost useless, the heater must be connected and switched on so drawing current.

012

Overheating at overheat sensor (Software threshold value)

Temperature of the overheating sensor too high. Check heating air path for crushed pipes or blockages, air outlets closed or blocked. Often caused by accidentally puting objects against heating outlets. Check if air pipes are too long or have too many bends. (Just replacing a straight outlet hood with right angle version can often put the piping outside specification.) Check pumped fuel volume. Check Overheat sensor. Check blower fan as fault code 33. The heater can be reset from fault codes 012 and 013 by switching off and back on. Overheating is a serious safety issue and can damage the ECU so find and eliminate the cause before resetting. More info on our Faults Main page, mainly in the Faults when running section.

013

Overheating at flame sensor (Software threshold value)

*Airtronic
Temperature of the flame sensor too high. Check as fault code 012. Check Flame sensor instead of overheat sensor.

014

Temperature difference between flame and overheat sensors too large

Temperature difference between flame and overheat sensors too large. Check as fault code 012. Check both Flame sensor and Overheat sensor.

015

Overheating lock out

This code displayed when the heater is switched on after fault code 017 was displayed. (I have no idea why this fault code is needed, code 017 covers the problem! On Hydronic water heaters the code is for 10 overheats in succession). More info in fault code 017.

016

Overheat - threshold temperature difference exceeded. (after FMP starts.)
PLEASE NOTE! Fault code 016 is only displayed if the heater is running and the water temperature at the overheating sensor has reached at least 80 °C

Temperature values of the overheating sensor and the surface sensor is too large. For remedial action see Fault code 012. Check the surface sensor: – Check wiring for continuity, short circuit and damage. – Measure the resistance in connector B2 – between pin 7, (black) and pin 8, (black), see page 47 for measured values

017

Overheating lock out (Hardware limit value)

The temperature exceeded the maximum the overheat sensor can measure. The ECU is locked for safety reasons. The ECU failed to recognise overheating fault code 012 or 013. My explanation on why 017 occurs is on the Faults Main page. Heat may have damaged the ECU, if not it can be unlocked using appropriate equipment. IMPORTANT Identify and clear the cause of overheating before trying to reset. This lockout is for a very serious safety problem. More info on our Faults Main page. http://altox.ru/

018

Glow pin – start energy too low

Glow plug energy input is too low

019

Glow pin – ignition energy too low

*Hydronic II only. Energy input less than 2000 watts. Check Glowpin, Check ECU

020

Glowpin interruption (Glowpin open circuit)

Check for broken wires. Check glowpin resistance, 0.42 to 0.7 ohms, 24v glowpin 1.2 to 1.9 ohms. Measuring accurately is not required for fault code 020. For fault code 021 use accurate measurement technique shown on Faults Main page and Airtronic Servicing page 2.Manual gives alternative method but few users will have a suitable high current 8v supply. Eberspacher advise that connecting to a 12v battery might destroy the glowpin but so far our users report they had no problem while doing a short duration test on 12v. Make sure leads include a fuse when testing for 021 code. Caution, glowpin will glow red hot if working ok.

021

Glowpin drawing excessive current or short circuit downstream of earth

Check wiring for damage. Check for water leaking inside heater and on connectors. Check glowpin resistance as in code 020.

022

Glowpin drawing excessive current or short circuit downstream of +

*Hydronic II only. Check wiring for damage. Check for water leaking inside heater and on connectors.

023

Glowpin 2 interruption (Glowpin open circuit)

*Hydronic II with second glowpin only. Check as code 020

024

Glowpin 2 drawing excessive current or short circuit downstream of ground

*Hydronic II with second glowpin only. Check as code 021

025

Diagnostic line fault Heater remains operational

*Hydronic II only. This fault may prevent diagnostics equipment working as it uses the blue/white wire. Check blue/white diagnostic wire for damage or short circuit.

026

Glowpin 2 drawing excessive current or short circuit downstream of +

*Hydronic II with second glowpin only. Check as code 022

029

Glowpin 2 ignition energy too low

*Hydronic II with second glowpin only. Energy input less than 2000 watts. Check as code 019

030

Blower fan motor not rotating or rotating at wrong speed

* this code not used Hydronic II. Check fan is free to rotate and not catching on anything. Check wiring for breaks, loose connections, faulty insulation. Check combustion air path, both inlet and exhaust, are not obstructed. Blower brushes or bearings worn. If testing motor on a dc supply use 6 or 8v, not 12v.(Measurement as described in D4WSC D5WSC manual is completely wrong)

031

Blower fan motor interruption. (Open circuit)

Check wiring for breaks or loose connections. Check resistance of fan motor. Resistance should be approx 0.5 ohms, accuracy not critical for this test. Rotating shaft slowly by hand while checking may reveal faulty segments. If testing fan use 6 or 8v dc supply, not 12v.

032

Blower fan motor short circuit to earth or drawing excessive current.

Check wiring to blower for insulation damage. Check for water leaking inside heater and on connectors. Check motor is free to rotate and not catching on anything. Check bearings are not starting to seize. Check resistance of blower motor which should be approx 0.5 ohms. Use accurate measurement technique shown on Faults Main page and Airtronic Servicing page 2. Replace motor. If testing blower use 6 or 8v dc supply, not 12v. http://altox.ru/

033

Blower fan motor rotating at wrong speed

*Hydronic II only. Check as code 030

034

Blower fan motor short circuit downstream of + or -

*Hydronic II only. Check wiring to blower for insulation damage and touching other wiring. Check for water leaking inside heater and on connectors.

035

Reel partial load relay - interruption

036

Reel partial load relay - circuit

037

Water pump not working

*Hydronic II only. Check water pump Apply 12v to water pump, connector B1 pins 12 and 13 (Power input max 4 amps)

038

Relay for operating vehicle fan interruption (Open circuit) This fault is not displayed by all heater types.

* this code not used Hydronic II. Check wiring to relay for breaks or loose connection. Check relay: Disconnect 8 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 2 and 3. Depending upon type of relay a good reading should typically be around 80 ohms. If greater than 1000 ohms check relay coil resistance or replace relay.

039

Relay for operating vehicle fan short circuit, overload or short circuit to ground.

* this code not used Hydronic II. Check wiring to relay for insulation damage or broken connection touching. Check for water leaking inside heater and on connectors. Check relay: Remove relay, if fault 038 displayed replace relay. Alternative method: Disconnect 8 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 2 and 3. Depending upon type of relay a good reading should typically be around 80 ohms. If lower than 20 ohms remove relay. Then if resistance becomes very high replace relay.

040

Vehicle Blower - transistor error

Remove relay, if fault code 38 is displayed, the relay is defective.  Replace relay

041

Water pump interruption (Open circuit)

Check wiring to water pump for damage or breaks. Check resistance of the water pump, rotate shaft by hand while checking. Disconnect 14 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 10 and 11. No resistance figure is quoted but probably about 0.5 ohms. If trying pump on 12v battery without water keep test very short.

042

Water pump short circuit to earth or drawing excessive current

Check wiring to water pump for damage to insulation. Check for water leaking inside heater and on connectors. Check if pump is running dry. Vent heater, check header tank water level. Disconnect connection in water pump cable harness. If error code 041 is then shown replace water pump.

043

Water pump short circuit downstream of +

Check wiring to water pump for damage to insulation. Check for water leaking inside heater and on connectors.

047

Fuel metering pump short circuit to earth or overload current

Disconnect the wires on the pump connector, if fault code 048 is displayed pump is faulty. (If the pump has to be replaced please donate the faulty one to us for science.) If code 47 remains displayed check the wiring to the pump with a test meter for a short circuit. Most likely cause is mechanical damage to the insulation where cables are clipped in position or uninsulated connectors on older Eberspacher pump types touching the chassis. Check for water leaking inside heater and on connectors.

048

Fuel metering pump interruption (Open circuit)

Pump connector not fully pushed home or making a bad connection. Disconnect the wires on the pump connector and measure the resistance of the pump. The resistance of the pump should measure 10 ± 0.5 ohms (24v 36 ± 1.8 ohms). If not ok check connections for corrosion, replace pump. If pump is ok check wiring to pump. Measure resistance from connector. If no test meter is available the pump can be pulsed with a 12 volt battery. Connect and disconnect from the battery, each time it should make a loud click. (Make sure the pump wiring is not connected before doing this test or you can destroy the ECU. Also take care not to accidentally short circuit the battery). More info Fuel 2 page.

049

Fuel metering pump short circuit downstream of +

Check wiring to fuel pump for damage to insulation. Check for water leaking inside heater and on connectors.

050

Too many start attempts. ECU locked out

*Hydronic II - The ECU locks out after repeated start attempts without flame detection. Hydronic - The ECU locks out after 10 consecutive start attempt failures. Manual is not clear, I think a failed start with the second start attempt counts as one failure. IMPORTANT Identify and clear the cause before trying to reset. This lockout is for your safety as each attempt leaves unburnt fuel. It can be unlocked with appropriate equipment.

051

Flame detected during switch on (time exceeded blowing cold)

Flame sensor resistance above 1274 ohms at switch on indicates the temperature is above 70 degrees C and the fan runs to cool it down.If temperature does not fall below 70 degrees within aprox 4 minutes heater is switched off. Check flame sensor: Disconnect 14 pin connector, measure on the connector part not going to the ECU. Measure resistance between pins 1 and 2. If reading greater than 1274 ohms replace sensor.

052

Safety time exceeded. Unit failed to start on both start attempt sequences

No flame was detected during the two start attempt sequences, flame sensor value was below 80°C. Unit shut down after a cooling down cycle. This is simply a standard failure to start fault indication. Most heaters checked will have this code in memory, usually it can be ignored as you will already know when it failed to start, it switched off without generating any heat. The causes are detailed in Faults Main page.

053

Flame cutout in highest power stage

The flame extinguished during the boost / highest power stage. Fault code is deleted if automatic restart is ok. The causes are detailed in Faults Main page in the section "Eberspacher starts normally but stops whilst running, it may try to restart."

054