- If you need clarification, ask it in the comment box above.
- Better answers use proper spelling and grammar.
- Provide details, support with references or personal experience.
Tell us some more! Your answer needs to include more details to help people.You can't post answers that contain an email address.Please enter a valid email address.The email address entered is already associated to an account.Login to postPlease use English characters only.
Tip: The max point reward for answering a question is 15.
The fault code P0420 is caused by the catalytic converter falling below minimum efficiency level as measured by the catalytic converter monitor sensor (similar to an O2 sensor, but different function). The cat is not covered for 120,000 miles. Here is the correct information on the warranty of the catalytic converter. The Federal Emission Warranty covers that part for a period of 8 years or 80,000 miles, whichever occurs first. So you are out by years in service and by miles.
Clogged catalitic converters can cause this. The engine will start and run for a bit, but as the engine tries to exhaust the gases they have no where to go. And this will shut th engine down. To check remove one of the 02 sensors in front of the converter. If it runs fine theres your problem. If the converters are clogged badly, your engine will run better, but maybe not as well as it should. the reason being is that the hole for the 02 sensor is not big enough to vent all the exhaust.
check engine light on when tested it says bad o2 sensor did you replace 02 sensor it takes driveing it so many miles before light will go off give it couple days you dont need cadillac converter check engine light will go off cv joint they click as you turn dont let a mechanic sell you something you dont need its very rare for cadillac converters to go bad its common for o2 sensors to go bad like yours did but when 02 sensors are replaced it takes driveing it for awhile before it resets itself you also have more then one 02 sensor was then wrong one replaced they screw into your exaust manifold
Here are a few things to look at:
Have you replaced the air filter? Have a compression test done on the engine, could possibly be a leaking vale. If any vacuum hoses have been removed from the engine they will have to be re-installed. Solid Lifters out of adjustment can cause incomplete combustion. Make sure engine is reaching proper operating temperature (eg. thermostat). Do not use low grade (octane) fuel for test.
Clean oil, tire pressure, brake drag?, every little thing counts.
If it was P0420 it is most likely a failing converter.It is better to let a mechanic tackle this unless you are good with a torch to replace the converter.just remember that your cat. converter has a 80,000 mile warrenty with GM so you may be able to get it replaced for free.
CODE PO420 CATALTYLIC CONVERTER SYSTEM FAULT.ITS SAYING FAULTY CATALTYLIC CONVERTER.IF IT BEEN A WHILE IF YOUR CAR HAS A WHOLE LOT OF MILES ON IT.YOUR SPARK PLUG CHANGE IS DUE AT 120000 MILES. DUE A LITTLE TUNE UP CHANGE AIR FILTER AND FUEL FILTER.SEE IF YOU HAVE ANY ENGINE FAULTS BAD PLUGS DIRTY INJECTORS ANY THING UP SET FUEL SYSTEM CAUSE CAR TO RUN RICH.EXCESSIVE UNBURN FUEL WILL GATHER IN CATALYTIC CONVERTER CAUSE IT TO BURN OUT.SHORTING LIFE OF THE CATALYTIC CONVERTER.