Question about 2000 GMC Jimmy
That code means that the catalytic converter is operating below it's threshold of efficiency. It could be that the cat is clogged which would necessitate getting a new one (the car would run terribly with almost no power) but more often than not the post-cat oxygen sensor is failing. That's the one between the cat and the muffler. Its only purpose is to serve as a comparator against the readings from the primary (pre-cat) sensors, to determine whether the car is working correctly. I'd change that, clear the code, and start driving to see if it comes back.
Posted on Feb 03, 2010
Catalytic converter below threshold due to engine needing tune up which leads to plugging of cat or replace 02 sensor if heater circuit has malfunction
Posted on Feb 03, 2010
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Posted on Jan 02, 2017
it means your 02 sensor pre cat is not working or the cat is no longer any good start with the 02 sen its easy to do and cheaper than the cat
Posted on Feb 19, 2009
the light can be caused by any one or combination of over 200 trouble codes, go to any kragen or Autozone parts store and ask for a trouble code test, it is free, then record the code(s) they come up with and post them back on fixya
Posted on Apr 19, 2009
SOURCE: P0420 code
This means that the secondary O2 sensor detects that the catalytic converter
isn't working as efficiently as it should.
This engine code can be triggered by any one of the following:
1.) The catalyst in the catalytic converter is cracked, clogged, or otherwise damaged.
2.) The secondary O2 sensor is malfunctioning.
3.) There is an exhaust leak.
4.) The computer unit is faulty.
Posted on Aug 24, 2009
here are a number of things that could be causing this p0420 catalyst efficiency code. The most common thing is the catalytic converter itself is no longer functioning properly.
The other likely thing is the rear O2 (oxygen) sensor is no longer working properly. Other things could include exhaust leaks, damaged exhaust pipes, damaged O2 sensor wiring/connectors, plugged catalytic converter, etc.
The easiest thing to do first is a visual check of things. Visually inspect the exhaust system for leaks, check the catalytic converter for dents, holes, severe discoloration, and check for a rattle inside. If any of those syptoms are there, the converter likely needs replacement.
Then, visually inspect the downstream O2 sensor (behind the converter). Check for broken wires, obvious faults, etc. If all that checks out, you'll want to check the operation of the O2 sensor. To do that, you'll need access to a scan tool or oscilliscope. Check that the waveform is pretty steady. If the reading fluctuates then the sensor is likely bad and will need to be replaced.
Try this, turn the ignition key to the on position, (engine not running) and pull the fuse to your ECM for 30 seconds and then re-install it. Once re-installed, start the engine and let idle for 1 min and then go for a test drive.
If the engine stalls, let it. The ECM is relearning the sensors and engine, just restart it and after 1 min when the RPM drops. God for a test drive and see if the service engine light comes back on and re-scan for the DTC codes and address the issues indicated by the DTC code.
Thank you for using fixya and good luck.
Posted on Apr 18, 2010
Tips for a great answer:
Oct 05, 2012 | 2006 Nissan Sentra 1.8
Sep 20, 2012 | Cars & Trucks
May 17, 2012 | 2001 Toyota Sienna
Aug 02, 2011 | 2006 Chevrolet Cobalt
Possible causes - Three way catalyst converter worn out
- Intake air leaks
- Fuel injectors may be faulty
- Fuel injector leaks
- Spark plugs may be faulty
- Improper ignition timing
- Engine Control Module
Jun 07, 2011 | Mercury Cougar Cars & Trucks
Apr 24, 2011 | 2005 Toyota Highlander
Aug 24, 2009 | 2002 Toyota Camry
Apr 19, 2009 | 2002 Pontiac Firebird
Mar 22, 2009 | 2001 Pontiac Montana
620 people viewed this question
Usually answered in minutes!