ok , i got the spare. I see there is no seal , should i just unscrew the old with the engine cold and replace with the new one?
Well what else could you do if you bought a spare without a gasket/seal? I suppose you could make one from some gasket material if you have some on hand, but if you have to buy some it’s probably cheaper to get another sensor!
Andrea, looking at the different brands of sensors available on rockauto.com there are basically two different styles:
The A type, with the straight body/thread, uses a sealing washer.
The B type has a straight thread but has a tapered/beveled seating section. It does not appear to use (need?) a sealing washer/gasket.
What type is your new sensor?
My sensor is of the second type, so I don’t need the washer I suppose. It is important to use a specific torque while screwing it?
There may be a torque spec, but with the tapered seat you should be fine if you just tighten it until snug. Basically finger tight plus a bit more. The Haynes manual (section 6.4) says to apply Teflon tape to the threads but I doubt that is necessary. After installing the new sensor start the engine and run until it reaches normal operating temp and watch for any sign of leakage around the base of the sensor. Tighten slightly if necessary and repeat if necessary.
A taper like that USUALLY seats onto a tapered seat, the two coming together is what makes the seal. If the hole on your car does NOT have a taper at the top then the replacement you have MAY sit a bit proud of the surface, I’m not certain it will, but if it does, that means that only the threads are providing a seal. IF you find a gap between the sensor and the flat face after screwing it all the way down ‘hand tight’ I would order the sensor with the sealing washer and use that.
i replaced the sensor this morning. I used just some teflon i the threads and i see not leakage at all. Anyway i am confused. With the new sensor the hesitation is gone, cold and hot, but i tested the old sensor in hot water and the readings are correct.
So i ask myself if it was a connection problem or other issue. If it was a connection problem probably it will show again in future. The sensor cable is tapered and i cannot see any sign of breakings and also the connector is in good shape and clean. Maybe the old sensor could have some problems that did not appear during the test?