Posted to Emissions Forum on 10/28/2013
Your repair reminded me of a similar experience that I had
had a few years back on a late-90s Toyota truck with no EGR,
no codes, and a significant ASM NOx problem. I was able to
determine that the HO2S was too lazy to keep the catalyst
happy, but not lazy enough to code.
A fresh HO2S made a HUGE difference in the NOx emissions,
enough to surprise me __and__ the bureau representative who
called me up after remotely viewing the passing report to
question .. er .. congratulate me on the success of the
repair. That was one of the few completed CAP repairs in
which I've participated that came in under the spending
limit with a solid pass.
Quick Stop Smog & More
Sacramento, California, USA