Coolant Temp Sensor

[Andy]

Hi all,

Me and Rich changed my coolant and thermostat today as the water was minging and gauge wasn't sitting in the right position.

Anyway apart from a few small hickups the change went well but the gauge still reads just below half.

I never thought at the time about changing or even cleaning the Coolant Temp Sensor which I presume is whats causing the inaccurate gauge reading??

Question is - If the CTS is buggered can this effect fuelling etc? Just thinking sensor -> electrical -> input to ECU telling it the car is cold still and to warm up more.

Thanks

[fireclown]

hi i think the coolant temp switch only does the gauge. i might be wrong. but these do play up quite a bit.

[Andy]

hi i think the coolant temp switch only does the gauge. i might be wrong. but these do play up quite a bit.

Thanks for the reply :)

Its worth asking because I haven't got a clue if it does tell the ECU or whether it does just what you say i.e. only supply the gauge with info.

[rickbee]

I had one of these replaced at VT last week. Engine management light was on and codes reading showed this part was the cause. No apparent fault with running of car. Light was only off for an hour, back on again. Go figure, car still running fine. If VT were right and the part is faulty, perhaps you should see it indicated?

[Richie-T5]

Andy, i would think if the sensor had an impact on the main ECU, you would get a fault code on the reader. especially if it can cause critical failures within the engine.

just a thought buddy

Richie

[John]

My sensor went the other week, came out to car turned on ignition, temp guage went straight to halfway and the car would not start, so the temp sensor was clearly telling the electronics the car was at normal operating temp, which it wasnt, like trying to start it with no choke. Left bonnet open for an hour in the sun and eventually got it going. New volvo temp sensor fitted all fine, but even with the faulty sensor ran fine once got it going. Did you fit genuine volvo thermostat, coud be it might be operating at a slightly different temp, which is why the guage is slightly down.

[racer]

Andy, according to the wiring diagram for the Motronic 4.3/4.4 the temp sensor talks to the ECU and the ECU drives the temp gauge.

Guess here, but I reckon that if your sensor is just reading low (through age or whatever) then the ECU WILL think the engine is cool. If the sensor had failed completely, then the ECU would see an "out of range" signal from the temp sensor and you would get the fault light on.

[Andy]

Thankyou very much for your help it is much appreciated.

In response to John yes i did fit a genuine volvo stat mate so it should be running as normal i.e. 90degrees.

Racer I thought the same, especially with the engine being ME7 (all stupid and complicated) !