Today I lifted the soundproofing off the top of the engine on my 300tdi and underneath the soundproofing there is a screw type sensor ( coloured blue in picture ) that screws into the head and the wire to it was rusty and freyed. Can anyone tell me what this sensor does ? I have included a picture if thats any help. Thanx

It's the cylinder head coolant temperature sensor for the Electronic Diesel Control.


Pete.

Cheers for the fast reply there Pete ! I do not think that this sensor was wired as the wiring was very badly connected but i suppose it could have been connected enough ! Is there any problem leaving it off for now or am i better renewing the connection with new spade connectors asap ? thanx again

To be honest I don't know, but I would expect to see higher fuel consumption and potentially black smoke, with it disconnected (you may also get the check engine light on the dash), I think that the ecu will use this sensor to determine the engine temperature and control the fueling with respect to engine temp.

Pete.

If it's a manual (ie not EDC-Electronic Diesel Control), it's just for the EGR control unit. (EGR only operates when hot).
So leaving it disconnected wont affect performance.

It'll affect performance even less if you blank off the EGR valve!

As it is an Auto I'll wager it does have EDC, however it may well still be for the EGR system in which case it probably won't make any difference to the performance as stated. To be honest I ditched all the EDC off mine when it started giving me grief and have now replaced that particular sensor with a thermocouple that allows me to read the water temp at the cylinder head.

Pete.

so if its for the egr, where do u plug in for the temp sensor? a question i need to ask

If you mean for the gauge then it's on the stat housing.

Pete.

This sensor is specifically to do with the EGR valve for cylinder head & exhaust temperature sensing.
If you have blanked off the EGR valve, you can dissconnect it or insulate the wires & leave them in situ, remove the electrical module with the air pipes leading to it - module is next to the wheel chock & jack on near side inner wing at front.
Block off all the little black pipes & tie them out of the way.

Performance will not change if the EGR is blanked off. May improve a little with the above.

You MUST block off the little black pipes/tubes or water could get sucked into air filter or engine.
I simply used M4 x 10mm bolts pushed into the rubber tube ends.

Job done.

Filthy