Faulty temperature sensor?

Hi guys.

I think i have a faulty temperature sensor. But i have no idea where it would be or how to replace it.

Happens randomly. Will be driving along, and the temperature gauge on the dash will be 1 or 2 bars full. Then out of nowhere it beeps at me and then all bars are full. After about a minute or 2 it will go back to what it was before.

Any ideas?

Thanks in advance

Vildar wrote: I think i have a faulty temperature sensor.

On a 16v Diesel engine, have a look by the fuel filter.

Coolant temperature sensor location: White arrow, green plug
You can find the right replacement engine coolant temperature sensor in this link to euro car parts website.

Sorry for the delay in reply.

So, a few things have happened since.

Recently my coolant temperature reading was staying on full. Continually. But the car was not overheating in the slightest. Was just staying full and beeping 3 times even from a cold start.

So i replaced the sensor, which made all the coolant spill from the car! (My own fault. I didn't make the connection that a coolant sensor is in coolant. )
After i sorted that, replaced the sensor, filled it backup. And started the car, made sure the air got expelled etc. Still the same problem. For about an hour. Then the reading reset back to normal. Hooray!!

However now, when i start the car i get the normal dash lights show up. Even the temperature ones. But nothing shows when ive been driving for ages. No lights light up on the temperature.

Could there still be an issue here or is it infarct not getting that warm?


Also, after reading around i kept seeing the mention of 2 sensors i may need to replace. But they kept referring to petrol cars. And that diesel only has one. Is this infact the case? As there is also a blue sensor looking plug further down the engine.

Vildar wrote:Could there still be an issue here or is it infarct not getting that warm?

After a run, carefully (because they could be hot) hold the top radiator hose to see if it is actually hot, do the same for the lower one.

This will show you if the cooling system is getting hot.

Vildar wrote:After i sorted that, replaced the sensor, filled it backup. And started the car, made sure the air got expelled etc.

The filling instructions are in this topic - Citroen C3 Coolant which includes the use of a header tank.

Vildar wrote:Also, after reading around i kept seeing the mention of 2 sensors i may need to replace. But they kept referring to petrol cars. And that diesel only has one. Is this infact the case?

Yes

Vildar wrote:As there is also a blue sensor looking plug further down the engine.

Can you take a picture and attach it here, by following these instructions 'How to attach images to the forum' ?

Had a look after I drove home from work.
The tubing at the top of the engine felt warm, but not that warm. Definitely not that hot. Could easily hold it.

The area where the green sensor plugs in was also warm. Again, not painful to touch.


The blue plug I'm on about is just visible in the middle of the first photo. Left of the battery and what I think is the ECU


Edited to shrink the photos. Sorry, didn't realize they were so huge.

Just wanted to post an update.
Down to this cold weather here, I had to defrost the car. So left it idkeing while I sorted it.

After a while the temperature gauge showed life!
So I'm now assuming it is actually working.

Thanks for all your help.

Does the car's cabin heater work OK?

The cabin heater works perfectly fine.

That's good news, I was thinking if you still had air in the cooling system or a faulty thermostat your car wouldn't get up to temperature, something you can sometimes feel through the heater with the cabin not getting as hot as usual.
If you find the temperature gauge never gets up to the normal level, both of the above (thermostat and air in the system) are things to look at.