Citroen C3 outside temperature indicater indicates wrong value

Usually means a new sensor .

Ok, thanks for your reply.
I'll need to find that sensor first.
(I've been looking around and read on some forums that its inside passengers door mirror. Is that right?)

Can the sensor be bought separately?

Thanks

Drivers (o/s) mirror . This should help you with the pics etc.

http://citroenc3owners.com/citroen-c3-questions/aircon-problems-external-temperature-sensor-on-52-reg-c3-t81.html

Ok great, thx!
I just found the sensor. As soon as I touch it with my finger, there's an imidiate increase of the outside temperature on the MFD.
As soon as I remove my finger, it tumlbes again down to bearly 1'C. It's supposed to be at least 7'C if my weather station is correct.

So it seems that the sensor is still working, but gradually shows a lower value.

As far as I know, the mirror never got hit or moved by anything.

The only thing I might be thinking of is this:
Last week I had to jump start my Landy (battery dead) ,connecting the Citroen's battery to my Landy's. It started almost immediately.
Could that have given the a bad impuls to the CPU?

Thanks for advising.

* Sorry, I meant ECU and not PCU ;)

I stopped jump starting from car to car years back as it can cause problems with ECUs , electrical circuits etc. on todays cars .Now I use a portable power pack to eliminate any possible chances of introducing any faults . I'm not really sure if that has caused it , but a possibility .Electrics are not my strongest subject , I employed others to do that side of the garage business . May just be faulty sensor .

Ok, thank you very much for your time and expertise. I really appreciate this.
And I must agree about not jump starting older cars with modern cars. I should by a portable power pack myself!

Anyway, I think I will try to reset the the BSI computer, as that might help to erase faults in the ECU. (That's what I read on the link you gave me in your previous post)

I'll keep you posted if that helped.
thx.

Glad to help , hope it works .If still having problems get back to forum and I'm sure you will get further help / advice if needed .

Sounds like the sensor as stated.Don't go resetting bsi just for the sake of it as you might cause yourself more problems.

Could be resistance in your a post terminal,s that,s giving a false reading ,would check and clean with electrical cleaner prior to replacing any sensor,s.

Ok.. first of all, thx for all your replies and help!

I tried resetting the BSI yesterday, but that didn't help. It only resetted the time and date displayed on the MFD. Other data like radio memory and on board trip data/fuel consumption were not resetted.

The outside temp. still indicates about 6-7'C lower than actual as soon as I turned on the ignition key.

As far as I noticed, nothing else changed.
So this leads me back to the sensor, or maybe indeed some electrical resistance issue. Where do I start by cleaning the connectors/headers?

thx

check the connector in the A post. Its a bit of a fiddle to remove the gaitor but check for any signs of water ingress or damaged wiring but to be honest i think i would just get a new sensor.

Indeed, it is a bit of a fiddle to remove that gaiter.. But I managed to check all the wires an fuses. There seems nothing wrong and certainly no sign of water ingress.
So that leaves me only with the sensor left.
Any tips on dismantling the mirror to get to the senor?
thx

its plastic!!!so be carefull. Carefully remove the colour coded cover and you may also need to remove the glass. I think the glass is just held by plastic barbs.The easiest way to replace the sensor is just cut and raychem or solder the wires together.I dont think you will need to remove the whole mirror.