1997 A4 coolant temp sensor

Haynes says........

On all models the coolant temp gauge/warning light sensor is located in the coolant outlet union on the left hand side rear of the cylinder head..............this obviously only applies to 4 cylinder engines. If you have a V look in the same area though. It does say the sensor can be renewed which I think would be obvious.

That is about a 10 minute job to replace the Coolant Temperature Sensor if the one for the FI is the same one. Right at the rear of the cylinder head. Make sure the engine is cold, loosen the coolant expansion tank cap and then retighten. This releases any pressure in the system and stops/slows any coolant loss. Then you can either pull the clip holding the sensor and pull the sensor out with the wiring plug attached. Then install your new sensor along with a new 0-ring after making sure the old 0-ring is out of the hole. Install clip and clip on wiring plug. You probably will not lose any coolant. ;-) BTW I don't think that sensor is expensive at the dealer, but call and check!

Thanks!

Have the same problem on my 1998 A6 1.8T.

Literally just picked up the parts from my local Audi dealer:

Temp sender =A326.79 O Ring =A31.00 Retaining Clip =A30.43

A good link describing how to change the sender on a 1.8T engine is:

It's for a Passat, but the engine in the Audi is exactly the same.

For other engines there are write up on Audi World:

Hope that's of help.

Just need to get around to changing mine now!