Thread: o2 sensor or catalytic coverter

Yessir.

If you can monitor graphing scan data, you can watch your O2 sensors. Bring the engine rpm up to 2500 and monitor your upstream and downstream sensors. Without getting too technical, what you are looking for is a distinct difference in the graphs. Make sure you are only viewing 4 PIDs so the refresh rate is quicker. If your downstream sensor is pretty much a mirror image of your upstream sensor, your cat isn't doing its job anymore. While you want to see a fair amount of cycling in your upstream sensor, you typically want a consistent and relatively flat graph for your downstream sensor. Hope this helps.

Rotten egg smell doesnt always mean a faulty cat. You may have more than just a catalytic converter problem. Do you know someone who can hook up a good scan tool and monitor your fuel trims? I have replaced alot of converters over the years that were being ruined by inefficient combustion and/or rich air/fuel mixture.

If the cat is plugged or close to it mileage will drop.

Originally Posted by chris99gtp

reset the code and it hasn't come on since how long should it take to go on? also does the converter ruin gas mileage

My advise is to have someone with a quality scan tool hook up the next time your light comes on. Check the freeze frame data captured by the PCM when it set the DTC. The reason I suggest this is: If the converter is failing, you want to make sure it isn't being melted down by something coming down the exhaust stream. A new converter will end up failing too if the problem isnt corrected. Not saying this is what you are dealing with but I would play it safe and have it scanned should the light come back on. Another possible fix is to find a shop that sells BG products and have them perform an intake and injector service. I have seen this service improve fuel economy and revive a sluggish catalytic converter. Just a suggestion.

Tony

Chris, get it to a shop that you trust. I get better gas mileage from my 01 3500 dually and its 8.1L