So my struggle continues with my 2001 legacy. I have a 5 speed 2.5L I have replaced the knock sensor, TPS, plugs, wires and fuel filter as well as both o2 sensors. My problem is the car keeps giving me a P0122 code. When it does this the car will jerk and buck as I drive it. The funny thing is that if I pop it out of gear and then rev the motor to over 5500 RPM it will run smooth for a while, aprox 20-100 miles, until it starts doing it again. FYI, when I replaced the o2 sensors I used an OEM one for the upstream but a generic one that I had to wire for the downstream because I was having trouble sourcing an OEM at the time. Also I have read that an EGT probe could cause such problems but I have been unable to find a reference to my car even having one. One person even suggested I may need an ECU or that I could just have some bad wiring. Any suggestions before I throw in the towel and just take it to a shop?

P0122 indicates a TPS circuit problem. One possibility is a bad connection at the 20-pin main engine connector, B21 -- the TPS connects to the ECU via three of its pins. You could check that connector for corrosion, etc. It's one of those near the rear of the engine, passenger side.

 

I just read your previous thread. Another thing to check is that the replacement of the pigtail for the TPS was done well.

 

A voltmeter probing at the ECU and someone to wiggle the connections while the meter is read could probably pin down the cause.

Okay, thanks I'll try it and let everyone know the outcome soon

I actually found two of those big connecters, one white and one orange. I was able to clean part of the white one and then I noticed a loose vacuum house. Plugged it up and now I've driven 200+ miles with no problems. Hopefully all will continue to go well. Thank you for the help!