Check Engine 22 - Knock Sensor broken? Or detecting knock?
 

Hi all. I'm getting a bit of hesitation when I put my foot down occasionally. A second after it happened today, the Check Engine light came on (MY99/00 Impreza Turbo 2000) with code 22 (Knock Sensor).

Does this mean the knock sensor is broken or that it is detecting knock and warning me?

If the latter, what are the normal causes of knock on these? It is fairly standard apart from HKS induction mushroom and 3" stainless. Not mapped (yet). Cheers.

Found a similar thread which didn't seem conclusive, but consensus appears to be to get a new one, clean the mating surface and be sure to not overtighten (23Nm).

Anyone know what part number I need for a Vreg GF wagon EJ20?

I'd get it checked out on a dyno, running a full decat without mapping can cause afr to shift and cause the nock

Detected knock will flash the CEL rather than keep it on constantly I believe. I had similar issues with my 97 T2000 along with the same code. When I removed the sensor it was cracked. Fitted the new one and torqued correctly and I've not had any issues since.

It's not a decat (sport cat I think - doesn't look like the standard item). But yes, I already contacted RaceDynamix - it definitely will benefit from mapping. I'll get a new sensor fitted. Cheers

Detected knock will NOT flash the CEL on a std UK classic.

The CEL/error code 22 you are seeing is due to the failure of the knock sensor, this can be caused by damp getting into the sensor as it outer casing cracks over time. if the CEL comes on in the morning (or when its raining) then goes out later on when the car is fully up to temp you can guarantee its a duff sensor that allows in damp as the engine heat dries it out so that it starts working again and the cel goes off.

make sure you get the one with the correct fitting on it, earlier knock sensors will not fit.

i fitted a 2nd hand one when i had the issue on MY99 classic and it cured it. there are other potential causes with the loom wiring rubbing through but the quickest option is to try a good second hand sensor.

My bad, I thought it did. Well, was told it did anyway.

Thanks Gambit. That makes more sense.

how did you go about getting to the sensor?
i have removed my TMIC and i think i can just about see it, although looks like i might need to remove some hoses, but cant see the electrical plug

HELP

There's no doubt it's a tricky one to get at if you've got big hands. Fortunately I don't and was able to get at it reasonably ok. I used a long 3/8 extension bar with a wobbly adapted on the end. It's a 12mm socket too. I unscrewed it and was then able to unplug the connector. Took me half an hour all together but I have a FMIC. Just make sure it's torqued properly (28NM?) and have a look at the old one to see what way it's positioned, I'm almost sure the workshop manual shows it at a particular angle as well.