(T) Preheat failure

Hi

I have a Fiat Stilo 1.9 JTD 2004. 3 months ago, I started getting a 'Preheat failure' message when I started the engine. It flashed for a few seconds and then didn't come up until I turned off the engine and started again.

I got it checked at various garages and till now have got all 4 glow plugs replaced, relay and bulk head checked. There is no problem now according to the mechanic but the failure message still comes up. He says the computer in the car is faulty and needs replacing.

I don't believe the garage as over the last few months, I have observed a pattern which the warning message follows. In March & April, when I started the car in the morning, the warning came up but when I started the car in the afternoon, when the weather was warmer, the message did not come up.

Since 2 weeks ago, when it is not too cold in the morning, say 15-16 deg outside, the warning message doesn't flash but when the temp is below 14 deg, the warning message springs up.

So, it has not got anything to do with engine temperature, coz I drive 1.5 hours to reach office and on cold days, even when I start the car just after turning it off (when the engine is really hot), the warning message flashes, while on warmer days, the message doesn't flash even when I cold start the engine.

Could anybody please tell me how to fix this problem?

I have already wasted over £300 in unnecessary glow plug replacements and other diagnostic fees.

Regards

Abhi

I assume the garage have read the fault codes and deleted them!!! When was the battery last changed as this can also throw errors up.
Aside from the error the car is starting alright isnt it, if so i shouldnt really worry about it but it will be worth checking your battery first.

Have a search for 'Preheat failure' message lots of info on this topic too.

Hi

I have not replaced the battery ever. But, there is no problem with any other equipment in the car and it starts alright everytime. Should I go to the garage to get the battery checked?

I am still quite amazed about the error message springing up when the outside temperature is below 15 deg. There is not message above this temperature. That's why I believe there is a problem with the temperature sensor. Are there any temperature sensors linked to this circuit? If yes, then where can I find them and are they replaceable?

Thanks

Abhi

You should always consider bad connections whenever anything is temperature related. Check around relay module and also the red 50A supply fuse near battery.

I'm not sure why you're changing heater plugs when they're not even faulty but I can tell you that the relay module can generate false intermittent errors itself.

I had an intermittent glow-plug error for over a year (plugs were fine) before I discovered the relay module was faulty although in my case it always worked at sub-zero temperatures (rather fortunately ) which if why I was in no great hurry to fix it