QuestionI HAVE A 1999 DODGE 1500 4X4 5.9. MY CHECK ENGINE LIGHT THREW A CAT 420 BANK 1 CODE SO, I GOT A NEW CADILLETIC CONVERTER. LIGHT CAME BACK ON, SAME CODE. HAD IT CLEARED AGAIN. HAD TO SIT IN TRAFFIC @ STANDSTILL FOR ABOUT 12 MIN & LIGHT CAME ON AGAIN. SUGGESTIONS?
AnswerHi Joy,
The code can also occur due several other reasons besides the converter:
The mechanical condition of the engine on that right bank of cylinders(excessive smoke from oil/coolant)
If the rear oxygen sensor was replaced when the cat. converter was changed, but the front sensor is still the old one, if that front sensor is 'aged' then that too can cause the code. So consider replacing the front oxygen sensor on the right exhaust manifold
Finally, check for an exhaust leak between the manifold and the converter and between the converter and the rear oxygen sensor, correcting any that you find.
I don't know which of these specifically applies but inspect for those possibilities.
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Thanks,
Roland
