‘Why is the engine management light on my motorhome flashing?’

Dear Alex,

I bought a 2006 Fiat Doblo petrol motorhome in April. En route to Dover in July, the engine management light (EML) came on; the Fiat garage in Maidstone said it needed a new radiator, timing belt and spark plugs, at a cost of £1,600. I couldn’t afford this lame house, where my local garage fixed all of the above for £500.

Having lost my holidays in France, I traveled to Wales where the EML returned. Another garage said it didn’t fire two of the four cylinders, so clean and reset the ignition; it worked for three days, then the flashing EML came back.

After doing a lot of research, my mechanic thinks the powertrain control module (PCM) might be at fault. Do you think the Fiat dealer is somehow culpable because their expensive initial diagnostic test failed to identify the real problem, even though they tried to ‘scare’ me into paying £1600 for repairs?

–PG

Dear PG,

There are a few points to discuss here. You mention that the EML is flashing, which on older Fiats like yours suggests there is a misfire. I assume this is confirmed by the codes output from the ECU, which is probably why garages have so far focused on one of the spark plugs.

However, misfires can also be caused by other issues, and on older Fiats like these, the ECU may generate error codes that do not necessarily refer to the problem in question. For example, a slightly worn cam or crank sensor can cause the ECU to suggest that there is a misfire on two of the cylinders. You may also have clogged injectors, and they may need to be removed and cleaned or, if really bad, replaced.

There is another possibility. These Fiats sometimes require a procedure called “phonic relearn” to be performed after the timing belt has been changed. This allows the car to relearn the positions of the camshaft and crank sensors; if this is not done, it may cause the engine management light to flash. It’s possible the garage did indeed fix your misfire by replacing the spark plugs, but didn’t perform a sound relearn afterwards (this is not a widely known procedure outside of Fiat circles , or commonly performed).

You can try it yourself. Warm up the engine first, then with the car stationary, the gearbox in neutral and the handbrake applied, rev the engine to 5000 rpm, hold it for three seconds, then let the rpm drop to idle. Repeat this procedure two more times, before stopping the engine and waiting a minute or two. If the EML has gone out when you restart the car, you should hopefully have no more problems.

If that doesn’t work, however, I suggest you take your Doblo to an independent Fiat or Alfa Romeo specialist. They’ll know your car better, and you may have more hope of pinpointing the problem, rather than trying to fix it by replacing expensive parts and hoping for the best — in effect, shooting in the dark.

As for the Fiat dealer, I don’t think they were trying to scare you – in fact, even though they charged a very high diagnostic fee, they might have done you a favor too.

They noted that the timing belt looked like it needed changing and your radiator was leaking, which is actually a good thing because if the timing belt was worn and broke, you might have suffered a much larger bill to repair the engine damage later. That leaky radiator could have caused coolant loss and overheating on your vacation, compounding your problems.

Yes, they’ve quoted you a lot to do the job, but any main dealer would do that too – their rates are always much higher than those of an independent garage like the one you ended up using.


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Kevin A. Perras