Is that the code you get from comp is PO420 eng light if so worst news either you have an exh leak between o2 sensor 1 and o2 sensor 2 or the front o2 sensor is lazy or the front catyletic converter is not working
basicaly code is only triggerd when engine is hot and the front o2 sensor and the rear o2 sensor read the same voltage when conv is working the front o2 sensor will fluctuate rapidly from 0v to 1v and rear o2 sensor will remain steady at 0.5v
try to explain best i can plz vote comment or reply if you need more help
Hello: If you have po420 catalyst low efficiency the only way to repair is to replace the converter' Before replacing the catalytic converter you need to make sure the engine is not running rich if it is it will destroy the new converter in a short time.
That's a pretty RELIABLE code!... You have a bad CAT (Catalytic Converter). Trust it to be accurate. The conditions which set this code is when the Upstream O2 sensor's data/signal is compared to the Downstream sensor's data/signal... when they are nearly identical, that's when this code is set (unless you have an exhaust leak).. If there is an exhaust leak.. repair it, then retest/recheck.
SOURCE: received fault codes P0420 and P1296 catalyst
Not sure on the P1296 code, however in 95% of the cases the P0420 code means the catalytic converter is bad. See P0420 and P0420.com
SOURCE: code PO420 catalyst system efficiency below threshold
you may have a bad converter, its not cleaning the exhaust, but on the other hand a bad rear o2 sensor can also cause this problem,there is a wat to test but you would need a scan tool or scope,replace the other sensor, if light returns then replace the converter, no money lost, if you were to replace the converter the o2 sensors should also be replaced. you have 165000 miles it would be crazy not to replace sensor and install new cat, so basically your just doing it in 2 steps and may get lucky and not need a cat. good luck.
Testimonial: "Your information is exactly what I needed to know.I suppose I just did not want to spend the money for a cat. converter. Thanks again for your help. "
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