I replaced the left side sensor (switch) for the AVL on my 2010 Impreza shortly before trading it in. I didn't use any sealer. It sealed just fine without it. There may have been some pre applied thread sealer on it, I can't recall.
But I have used that on other things oil related without any troubles. There is supposedly a Teflon sealant specifically for use with oil, but I have not had any issues using the regular stuff.
It is probably a better choice than using Teflon tape, as that might interfere with the grounding of the switch.
That is not a 'thread locker', it is a thread sealer. It is most often used to seal threads in like hydraulic systems. There is a trick to not contaminating your system with this type of thing, ensure the first couple of threads inserted are bare. If you put sealant all the way to the end, you run the risk of contaminating your system.
One of my little secrets is to use similar product on bolts to prevent seizing.
@Theseus161 I'm under the impression Teflon thread sealing tape is impervious to gas & oil. I normally use the yellow Teflon thread sealing tape, which is "double density" & is often labeled as "Gas type". Teflon tape.
Thanks, I will check for continuity from the sensor body to the head before starting the car. And keep an eye on the threads for leaking over time. I bought the new unit from the dealership, discounted it was $25, autozone sells for 15, gas anyone used duralast sensors?
The problem with almost all inexpensive sensors is durability. This is a pretty harsh environment and the device works all the time. The money is in durable construction and accuracy under harsh conditions.
This is basically a pressure switch. The biggest issue with both the cheap ones and OEM is they leak and occasionally the contact goes bad.
It is exactly the same switch that Chrysler used for the idiot light in the dash.
In this application, it only confirms to the PCM that the solenoid valve changed state.
I changed mine both because it was leaking oil, and it was beginning to randomly fail to make contact. I didn't want a CEL when I traded it.
Teflon tape in my experience using it has never held up for engines where you have oil and heat. It just doesn’t last long. An example is the pcv valve. The FSM calls out for liquid gasket.
Threebond 1215, which is oil and heat resistant.