406 2.0hdi cooling fan and temp gauge

[deanthedude1977]

Hi all--first post for me so please be gentle--
Recently bought a 2003 2.0 hdi 406 estate--first ever diesel or peugeot for me.

I noticed that the temp gauge is a bit erratic eventually gets to 90 then drops to nothing--sometimes notice headlights flicker very slighty whilst it does this-after reading here am i right in thinking change the temp sensor on right hand side of engine?
It looks easy enough to do and is held in with a clip--it has a green end and connector going into it--can i just pull old one out put new in and top up any losty coolant??
I read that if i turn AC on or unplug the sensor the fan should cut in(ive only one fan)it doesn,t so am wondering if my fan is shot or maybe relays/resistors?
Ive read similar posts but none quite the same probs as mine

Any help appreciated

Thanks

Deano

[madmadmax]

there should be a gray relay near the battrey that controles the fan

[deanthedude1977]

Thanks for reply

i have seen that--it actually looks quite new--i unplugged and sprayed with wd40--didnt seem to change anything--maybe faulty?

I,ll change the coolant sensor tonight and see if anything changes with fan or temp gauge.

[deanthedude1977]

update--i changed the coolant sensor--that fixed the temp guage--not sure bout the fan as temp never went over 90 even at idle for 15-20min
I did turn air con on and it blew nice n cold but didnt turn fan on?
As mine is the DW10ATED im being told/read this may be normal and wil wait till summer to see if becomes an issue--if it is will tackle then.

[Doggy]

Could well be OK. Yours is a late, fully-multiplexed car. On the earlier ones the fan(s) run at low speed if the a/c's on, but on yours it will only run if the water temp or the condenser pressure is high.

[deanthedude1977]

@ doggy--yeh thats what i read so i may be ok---thanks again for advice/help
great forum--i think the next task i will do is a service---still showing 4000 till next service and that ties in with the history i got with the car--

From what ive read looks easy enough--

Deano

[madmadmax]

just unplug the coolant sensor and start the car the fan will run full speed just a word of cation don't do that and have the fan in your hand as it will stay spinning for sum time