IM GETTING THE PO420 CODE ON MY 2003 4.3L V6 CHEVY S-10, I RECENTLY CHANGED OUT THE CATALYTIC CONVERTER, A COUPLE WEEKS LATER MY SERVICE ENGINE SOON LIGHT CAME ON. SINCE THEN I HAVE PUT IN NEW AIR FILTER, SPARK PLUGS, SPARK PLUG WIRES, I ADDED A BOTTLE OF GUMMOUT FUEL SYSTEM CLEANER TO THE GAS TANK, ALSO HAVE DONE AN OIL CHANGE,THE LIGHT IS STILL ON!! ANY HELP/SUGGESTIONS WILL HELP
THANKS FOR HELP
OSCAR
Hi
The code means---
Catalyst Efficiency
Below Threshold
(Bank 1)
Please make sure there is no air entering the engine behind the maf, such as a vacuum leak or leaks in ducting between the maf and the throttle body.
If that's no the case then its an issue with injectors clogging and they are not working due to "fretting". This "fretting" is electrical terminals to injectors getting oxidation on them and is fixed by unplugging them and replugging them in. The fix is to put a small dab of die-electric grease on the terminals.
I would suggest an injector service with the new GM procedure using "Top Engine Cleaner". This may be all you need but that P0420 bothers me. P0420, Catalyst System Efficiency Below Threshold, can be set by a poor connection at the PCM or a damaged wiring harness.
Please rate this soluton as FixYa if found useful.
Thanks
Rylee
Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
Inspect the downstream heated oxygen sensor (HO2), replace if necessary
Replace the catalytic converter if the error still doesn't go.
Please revert for further clarifications.
Thanks
Rylee
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I have a 2000 chevy s 10 4.3 4wd that ran good then it started hesitating like it has no power , after warming up and trying to go more than 25 pmh, checked plugs , wires, distrib all seems good any ideas???
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HOW MANY OXYGEN SENSORS DOES MY TRUCK HAVE?AND WHICH ONE IS AT FAULT?
I HAVE DISCONNECTED THE BATTERY ALREADY, DIDNT WORK
WHERE CAN I FIND THE ELECTRICAL TERMINALS FOR THE INJECTORS??
WHAT DOES PCM STAND FOR?
i have a 2001 s10 2.2 with the same code. i am being told to flash the computer the parimeter is too small, its running too rich because the computer thinks the engine is always cold, and some other things. i replaced the conveter and o2 sensors twice! i am taking it in for a total engine diagnosis tomorrow, not a scanner. the scanner says the converter is bad!!! if so, why the running rich????????
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