Hi. I need a little advice as I am not a mechanic and only modestly knowledgeable regarding todays cars.

I recently bought a 2000 Camry, 2.2 L California emissions, 5 speed manual with 72,000 miles. Shortly after I bought the car, the CEL came on. I bought an Autoenginuity ST06 scanner, and pulled the codes showing problems with the S1B1 wideband AF sensor heater circuit. Bought a new Bosch wideband sensor and installed. Cleared the codes. Fine for a day and CEL comes on again. Shows code P0420 catalytic convertor.

In doing research, I realize there are a number of factors that can influence this code. So I scan and record while driving. B1S1 voltage shows a pretty classic waveform pattern within normal range. B1S2 (post cat) voltage fluctuates wildly to the inverse of B1S1. Essentially, when S1 spikes up, S2 voltage drops to 0 or near 0. Not the pattern I expected.

Maybe related and maybe not, when driving at a stable speed and RPM around 2000, engine timing advance would go into the red zone. Not during acceleration, but when cruising. I have no clue as to what causes this or how to correct.

I have an Excel chart showing the relationship of the S1 and S2 voltage changes over a period of time if anyone is interested.

Any suggestions?

Thanks!

 

No one has anything to offer on my problem? Am I in the wrong forum?

 

I would tell your story to a qualified mechanic - call up the service department at the Toyota dealership and tell them exactly what you wrote here. I bet they will work with you to find an answer, maybe even from a technician.

You have a very technical question and I thought I would lead you in some sort of direction. I don't expect any thanks from you, I know I'm not helping.

 

I will thank you Matt. You took the time to respond, and I appreciate that. Actually, the advise I received from another forum is to replace the after cat O2 sensor first with a planar sensor, and see if that doesn't do the trick. Then work my way along from there, possibly replacing the cat itself as a last resort.

Thanks.