Many if not most Eberspacher faults can be identified and repaired by a reasonable DIYer, saving expensive dealer repairs.
Our pages are aimed at owners who do not have a diagnostic tool to help them identify the fault.
Much of the information here is readily available from the Eberspacher manuals and from other sources.
Although the pages are for D2 and D4 Airtronic and D1LC Compact heaters, most sections apply to other models.
This page deals with the simplest and most common faults and is a good starting point before progressing to the main faults page.
The most common Eberspacher faults
The commonest faults are due to:-
1 Low voltage, poor electrical connections or no power
Low Voltage is usually due to a discharged battery but there can be other causes.
Usual symptom - Eberspacher shuts off 20 to 40 seconds after switch on.
Note also that leisure batteries often deteriorate badly without users knowing.
It is important to realise that it is the voltage at the heater that matters, not at the battery terminals.
Low Voltage page deals with solving low voltage problems in far more detail than any other web source.
Poor electrical connections.
Many intermittent problems are caused by corroded or loose connections or switch contacts.
They are one of the major fault causes for older heaters as they have had more time to corrode.
No power is covered on the Eber Faults 2 page, Stage 1 faults.
Usual symptom - Nothing happens when switched on, no controller light.
Check fuses, broken or loose wires.
2 Fuel supply
Various symptoms - the most common being non starting or flame out shutdowns.
As a first step check you have sufficient fuel. Note the end of the fuel pickup tube is usually between 1 and 4 inches above the tank bottom to ensure there will still be fuel left to run the engine. This can cause users to think the heater is faulty as there is still fuel in the tank and the engine starts ok.
Fuel Problem page deals with checking the pump, fuel filter and many other fuel supply faults.
3 Eberspacher in need of a mechanical service.
Usual symptom - Heater starts with difficulty, often on second attempt and / or smokes whilst starting.
As a first step replace the glow pin screen, it should be replaced annually and can be done without removing the heater.
Older generation heaters D1L D3L D5L do not use a screen.
Also check the the glow pin chamber breather hole and the fuel filter.
Eberspacher heaters should be serviced every 2000 hours or every 2 years for low usage heaters.
D1L D3L D5L heaters are probably better off being left alone until problems arise.
Service may need to be done more often for some fuel types.
Service page shows DIY servicing details.
4 Air and exhaust pipes and silencer obstructed or partially blocked.
Usual symptom - Difficulty starting. Overheat shutdown - heater does not try to restart until switched off and on again.
(More serious overheating faults will lock the heater and need diagnostic equipment to reset)
Check air inlet and output ports and pipes for obstruction or crushing.
Check combustion air inlet and exhaust pipes for obstructions.
Check silencer, this can be blocked with carbon deposits even if exhaust pipe looks reasonably clear.
Old models do not automatically reset after overheating, they have a reset switch on the top of the heater under a rubber bung.
These are probably responsible for more than 8 out of 10 Eberspacher faults and do not require much expertise to solve or repair.
Hence they can be a easy point to start troubleshooting before doing the more detailed fault investigations on the next page.
Even if you do not find the fault and have to go to an Eberspacher dealer you will have lost nothing except a little time and effort.
Faults Page 2 shows more detailed Eberspacher troubleshooting and fault diagnosis
The D1LC and some early D1LC Compact heaters produced between 1990-1998 lock out after 5 unsuccessful physical start attempts (each attempt means two automatic starts to give the 10 starts before lock out).
One user confirmed the D5L has the same lockouts.
If the heater starts during these attempts it cancels previous non start fault codes and five new attempts are now available.
However should the heater lock out after these five unsuccessful physical start attempts then you will need to get it unlocked.
It can also lock out after 3 successive overheat faults.
I don't know how common these lock outs are but most people will try several times to start the heater when they have a problem.
We have several reports from users who had no lockouts despite doing many start attempts so would have expected problems.
In fact we have only met one locked out heater (D5L) which leads us to suspect it may not be as much a problem as expected.
A locked heater usually has to be unlocked by an Eberspacher dealer or with a diagnostics tool.
We have a diagnostic unit with reset facilities for this purpose.
It seems to be very poor engineering design by Eberspacher to not provide a way of resetting without special tools.
Eberspacher Airtronic D2 D4 D5 lockouts.
Airtonic heaters will lock out after 255 identical minor faults. Any different fault before lockout occurs will reset the counter.
Major faults, usually overheating, will lock the heater, possibly after 10 faults but exact details are not published.
'Overheat with excessive temperature' fault conditions will lock the ECU immediately, details on next page.
Providing no other components are damaged the ECU can be reset with equipment like the diagnostic unit, 7 day timer, 701 or 801 controller.
Fault Finding Page continues with more detailed Eberspacher troubleshooting and fault diagnosis.
Before doing any tests ensure the battery is well charged and in good condition.
Leisure batteries often are not regularly replaced and can deteriorate badly without users realising.
This causes many problems, the easiest way to eliminate is by substituting a known good battery.
Also check all connections for corrosion.
You use any information and advice we give entirely at your own risk.
If you do not accept this do not use this site, go to an Eberspacher dealer.
We have tried to make it as accurate as we can but accept no liability for errors or problems caused by following our pages.
Some of the information is only suitable for people with a good aptitude for mechanical and electrical repairs.
Any DIY involves some risk of accidents and you must decide if you are capable and can do it safely before carrying out any work.
You should also ensure your DIY is done to a professional standard in order to avoid creating potential hazards and insurance invalidation. Boat installations must strictly comply with Marine regulations.