Powertrain Control Module
 

My engine occasionally throws a CEL during normal driving, it goes away in about a minute or two. I bought the car knowing about this from the owner, who took it to a Subaru dealership, they claimed this code was resulting from a faulty PCM. Has anyone had to replace theirs? Where is it's location in the car?

thanks!

Check the codes for the check engine light yourself. There are full directions in the how-to documents. Let us know what code you get and we can go from there.;)

28 Knock Sensor No. 2 (SVX, Left Side)
32 Oxygen Sensor or Circuit (No. 1, Right Side, On SVX)

Then chances are it needs a new knock sensor and O2 sensor. The knock sensors are known to go bad after some time and the O2 sensor maybe just due to be replaced. Do you know when they were changed out last? Other things can cause the O2 sensor code, But chances are the knock sensor definitely needs replaced.

That left side knock is a pain to get to :mad: :mad:

I think there are many of us that get the occasional O2 Sensor... if you let up on the gas while climbing a hill??

I'd check out the knock sensor and correct that problem, if you're still having issues with the O2 sensor causing a fault, then work on diagnosing that problem.

I have reciepts from the previous owner,

removal and replacement of 02 sensor (7797021) on 5/7/03

removal and replacement of 02 sensor (22690AA180) on 7/12/05,
along with mention of a bad ground wire to the PCM, which was also repaired

No info on knock sensor

How hard is it to replace 02 sensors, is it something I can do myself?

A knock sensor is there to make sure there is no detonation or knocking in the engine, correct? If I always make sure to use 91 octane or higher do I NEED the sensor? can I clear the codes in the meantime and see if they come back?

Okay, I've done my searching of the forums and it seems the O2 sensor and the knock sensor aren't going to be too challenging for me. The previous owner seemed convinced that it was the PCM, I guess I'll find out when I'm done. Should I replace both left and right knock sensors while everything is apart, or just do the one for now?

If your going to lift the intake manifold to do the knock's then you should plan to replace all the vacuum lines under there also.

Most of the how-to's say you can just take out the alternator to access the knock sensors. I don't really have time (daily driver) or money (in college) to replace hoses. 1stsubaru parts lists knock sensors for $50 a pop, but $93 for a single o2 sensor.. damn

Walker $50
Denso $75
Bosch $90

all are listed as OE spec, does it really matter? I just want the CEL codes gone

when it comes to O2 you get what you pay for and there is NO way around that... you can go cheep on a knock sensor and you shouldnt have any problems