Temperature Gauge Sitting at 1 O'Clock (2002 S40 T4)

[Volvophile]

I have had the coolant temperature sensor and thermostat changed recently in my 2002 T4 Auto, but cannot find the reason why the temperature needle is settling above midway on the gauge. There is no sign of headgasket failure or any other indication to pinpoint the problem.

Could it be likely that the odometer cluster temperature sensor is faulty?

[neanderthal]

could an air lock cause this ?

[TEEKIZZLE]

This is after driving or just letting it idle to operating temp?

[bobthecabbage]

The temp gauge lies to you. Mine reads 12 o'clock from about 56C all the way up to 83C. Never seen it go above.

Only way to tell what it really is is viewing the live data with a code reader.

[cheshired5]

Originally Posted by Volvophile

I have had the coolant temperature sensor and thermostat changed recently in my 2002 T4 Auto, but cannot find the reason why the temperature needle is settling above midway on the gauge. There is no sign of headgasket failure or any other indication to pinpoint the problem.

Could it be likely that the odometer cluster temperature sensor is faulty?

Airlock, physical blockage, thermostat incorrectly fitted and oriented, incorrect temperature thermostat, faulty ECT sensor, faulty cluster....... Probably in that order too.
If your temp gauge wasn't over reading before the thermostat change, it's unlikely to be the case now.

[DXMachina]

is the coolant sensor an NTC or PTC type? if PTC, then resistance rises as temperature rises, and a loose connection would cause the temperature to display higher than actual

Most sensors are NTC though - high resistance when cold, low when hot , meaning a failing connection causes under-reporting of temperature. So its unlikely to be a simple electronic glitch.

Why did you have the sensor changed? did you suspect it was faulty? it could be you were right......

[skyship007]

Did you fit a non Gen Volvo thermostat or sensor ??

[Volvophile]

Originally Posted by DXMachina

Why did you have the sensor changed? did you suspect it was faulty? it could be you were right......

I thought it might have been the problem. I think it was faulty too, because there were other symptoms the car had prior that are now gone since the change.

Originally Posted by skyship007

Did you fit a non Gen Volvo thermostat or sensor ??

No, genuine Volvo part. Rarely put anything spurious into my cars.

I have changed the coolant, temperature sensor and thermostat. The car has also been plugged into a diagnostic reading which only threw up a faulty lambda sensor, but I don't think that would have any effect?

Maybe the sensor for the cluster is what needs to be looked at next.

[bobthecabbage]

You need to know what the temp the ECU thinks it's seeing in order to decide where the fault may be.

As I said what the ECU chooses to display on the dash on my V40 does not bear a linear relationship to the actual temperature reported by the ECU to my code reader.

Its as if the ECU has a normal range which it reports as 12 o'clock regardless of the actual temperature. In which case your coolant temperature is either quite far out or your dash interpretation of the 12 o'clock signal is wrong (and of course there is the option that the sensor is giving a false reading).

[ww1dm1]

Originally Posted by bobthecabbage

The temp gauge lies to you. Mine reads 12 o'clock from about 56C all the way up to 83C. Never seen it go above.

Only way to tell what it really is is viewing the live data with a code reader.

Exactly what I noticed! My temp gauge acts extra nice, rises up quickly and locks in the middle every time. But when I hook up a scan tool I notice that it's sitting at the same spot even when the actual temp is 70 degrees and stays there even when 100 degrees are reached and the fans go on. The gauge is bull****.