YFZsandrider
New member
I have a California emissions 2000 Limited 3.4 4WD with 200k miles.
Several months ago I threw a CEL, and it was showing a p0420 code. I know from the previous owner that the upstream O2 sensor is only about a year old, and is the correct Denso unit. After reading several threads, I replaced the rear(downstream) O2 sensor with the correct Denso part. After disconnecting the ECU, the same code immediately returned on startup.
I also read a few places online where people have had luck with cleaning catalytic converters. I tried this by removing my downstream cat and soaking it in a bucket of detergent and degreaser. After reinstalling and resetting the computer, the code went away and stayed away for about a month.
Now that the CEL has returned and remained on for the past 5 months, and now I need a more permanent solution so that I can pass state emissions.
I've searched here and Yotatech, without finding much of a good solution for the problem. I'm about to pull the trigger on a front and rear set of cats from Walker Exhaust. Anyone have any good recommendations?? Also, I'm not real interested in the URD circuit simulator because I want to fix the problem, rather than tricking the computer into thinking there isn't one.
Several months ago I threw a CEL, and it was showing a p0420 code. I know from the previous owner that the upstream O2 sensor is only about a year old, and is the correct Denso unit. After reading several threads, I replaced the rear(downstream) O2 sensor with the correct Denso part. After disconnecting the ECU, the same code immediately returned on startup.
I also read a few places online where people have had luck with cleaning catalytic converters. I tried this by removing my downstream cat and soaking it in a bucket of detergent and degreaser. After reinstalling and resetting the computer, the code went away and stayed away for about a month.
Now that the CEL has returned and remained on for the past 5 months, and now I need a more permanent solution so that I can pass state emissions.
I've searched here and Yotatech, without finding much of a good solution for the problem. I'm about to pull the trigger on a front and rear set of cats from Walker Exhaust. Anyone have any good recommendations?? Also, I'm not real interested in the URD circuit simulator because I want to fix the problem, rather than tricking the computer into thinking there isn't one.
