pre heat problem

[chrisgolf0]

"pre heat fault"appears on my Fiat stilo 1.9 diesel.what does this mean what is the cure ?

[TonyBeeeee]

Diesel engines have what are called glow plugs, they are electrically heated devices in the cylinders: they operate for a short period before the engine starts to assist combustion when the engine has not been running.

Exactly how Fiat tests for "pre-heat" I don't know, maybe they measure the current drawn by all the glow plugs? If one has failed less current would be drawn so a current test would be a reasonable thing to do.

You may not be able to tell in warmer weather, but in colder weather if it only fires up on 3 cylinders at first that would also indicate a glow plug problem.

[david1702198]

if a diesel is misfiring it would not be down to a faulty glow plug as they dont operate once the engine is running they are only to assist when starting from cold.

[TonyBeeeee]

Yes david I fully agree. but who said anything about it only happening when it is running? and do you know whether Fiat Stilo fault indicators remain on all the time, regardless of whether the problem is apparent at that instant?

Is it not true to say that many modern vehicle warning systems need to be reset by connecting diagnostic equipment?

[TonyBeeeee]

Oh... and who said it was misfiring?