Engine Temperature - erratic! (C8 2.2Hdi)

[brittleware]

Ok, cold engine - after less than a mile the gauge shoots up to 130c - with accompanying warning beep and red light. After about a minute, gauge drops to the expected below 50c as engine not yet warmed up at all.

Park for an hour - gauge now remains stuck at bottom of range for 10 miles or more - but cabin heater working nicely. Switch off.

Restart, all fine, temperature at the normal 90c.

Is this the sender? Or the BSI? (I have cleaned the contacts at the sender!)

TIA.

[6speedmanual]

I had similar problem on a Pug 406 HDi. The give away on this is the high readings waaaaaay before the engine could have overheated.

It was caused by a failed temperature sender unit. Found a new one on ebay for less than £10.

If it is not that but the electronics in the BSI then "shrugs shoulders in a Gallic sort of way" further work may be required using a diagnostic kit..... but I reckon the sender is fair bet.

Peter

[brittleware]

Thanks Peter - I'll try that first. I do have a LEXIA/PP2000 but no faults are reported (rubbish there are shed loads elsewhere!) in the cooling department.

Cheers,

Chris

[myglaren]

Same here with my C5. Would indicate coolant overtemperature for a few minutes after starting from cold then drop to normal after a couple of minutes.
New sensor fixed it and improved performance.

[Mandrake]

Thanks Peter - I'll try that first. I do have a LEXIA/PP2000 but no faults are reported (rubbish there are shed loads elsewhere!) in the cooling department.

You can monitor the engine coolant sensor reading in real time under the view parameters section of diagnostics on the Lexia, that will be a lot more useful than checking fault codes.

However depending on the engine model there may be separate coolant temperature sensors for the ECU and the dashboard gauge, in which case a faulty sensor for the gauge would not affect the data going to the ECU nor log a fault code or affect the running of the engine.

[brittleware]

Same here with my C5. Would indicate coolant overtemperature for a few minutes after starting from cold then drop to normal after a couple of minutes.
New sensor fixed it and improved performance.

I've fitted a new sensor. Wife is now out road testing* the thing - which right after fitting declared an anti-pollution fault! (Not an unusual event, I'm hoping that the new sender/sensor does a better job of fuelling via engine management)

*She had to use the car before I could test

[brittleware]

Sorry for the delay - the new sender cured the problem, and I suspect got the BSI fuelling the motor much better. Still having the occasional anti-pollution fault message, but thinks it's the EGR valve. New one sitting here in garage, but looks like a horrible job!