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Okay, I'm helping my girlfriend troubleshoot her legacy long distance. I have worked on the car quite a bit myself previously & am quite familiar with it. Today she was driving home from work & her check engine light came on. I ran her through how to check the codes & she came up with codes 41 and 22. I know she did it correctly because she watched me do it previously when the car threw the SAME CODES. Last time it threw them, however, we were certain it was because we'd left a crankcase breather hose disconnected from the intake (after MAF) and the engine was sucking un-metered air. After re-connecting it, the light stayed off for a few weeks. The car is still mis-firing & idling REALLY rough & we've been trying to figure out why. I recently replaced the head gaskets & noticed that the previous owner rigged up & spliced on a Ford o2 sensor. So I'm thinking: The ghetto o2 sensor is causing code 41 (A/F learning control/faulty learning control function)). This, in turn, is causing the engine to misfire and cause code 22 (knock sensor) to come up. How does this scenario sound to you guys? Have you seen many funky o2 sensors cause the ecu to throw code 41? Anyone have any past experience with either code or a combination of both? Thanks in advance, Kris.

Hi Kris,

Your scenario with the 02 sensor sounds plausible. That or the wiring that was rigged up may be bad, and causing the problem.

I'd start with replacing the O2 sensor with a new one meant for the car, reset the ECU, and then see how things run.

Finally had the chance to swap out the o2 sensor today. It's not significantly smoother than it was before, but it is smoother than it was prior to swapping it out. Thing is, it still briefly threw a knock sensor code (22), but not an A/F learning code. Which means - we're still misfiring for some reason. I've also noticed that when at idle, the car is almost totally smooth when in drive or neutral, but once the car is put in park it gets noticeably rougher. Might this have something to do with the transmission rather than the motor? Ideas?

The KS in the <'95 Legacy were prone to cracking, which will throw the 22 code. Have you checked it?

It'll leave the car in 'limp mode'...not sure what the ECU does to the tuning to compensate.

TD

P.S. Read THIS thread, a few posts down, from one of our most knowledgeable members, VRG3.....Next to Josh, of course.

Awesome call on the knock sensor. I just went & checked it out & while it does have a white connector, the black round part does have 3 cracks in it. Definitely worth swapping out!