Question about 2000 GMC Jimmy

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Service engine light comes on code is p0420 - 2000 GMC Jimmy

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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

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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

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Posted on Jan 02, 2017

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SOURCE: '02 civic engine code P0420. What does this mean?

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

emissionwiz
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SOURCE: p0420 code shows

P0420 Catalyst System Efficiency Below Threshold (Bank 1)
You have a worn out catalytic converter.

Posted on Apr 17, 2009

emissionwiz
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SOURCE: service engine light comes on , p0420 code

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

morse008
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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

Molson02536
  • 3854 Answers

SOURCE: I have a 2001 chevy S-10 2.2 liter. What does Code P0420 mean??

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

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What is wrong when this code shows up p0420 shows up..This is a 2006 nissan sentra


P0420 NISSAN - Catalytic Converter Efficiency Below Threshold Bank 1

The most common cause for the OBDII code P0420 on Nissan vehicles is the three way catalytic converter Bank 1 has reached the end of its useful life.. Since this is a very expensive part you need the code fully diagnosed as some other things like exhaust leaks or poor engine tune can cause it as well

Oct 05, 2012 | 2006 Nissan Sentra 1.8

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2001 Toyota Sienna CEL displayed code P1150 & P0420 what could be the problem


Mine is a 2001 Sienna LE. I got the P0420 code and the dealer want to replace an engine control computer for $1600. I've found posts that say you can replace your oxygen sensors, which still costs around $100 each. The P0420 seems to be emissions related. When my check engine light comes on, I run the highest grade, no ethanol gas, and usually within a couple of tanks, the light goes off again. The last time it happened about 2 wks ago, I put in the 93 octane no ethanol premium and a can of Seafoam and within a half a tank, the light went out. Your problem might be more serious, and I don't know what the 1150 code is, but so far that's worked for me.

May 17, 2012 | 2001 Toyota Sienna

1 Answer

2006 chevy cobalt(85000 miles) check engine light comes on and stays on. I am getting the check engine light code p0420. Engine seems to be running smoothly.


http://www.obd-codes.com/p0420

TSB Number: 3316 NHTSA Number: 10017210 TSB Date: n/a Date Added to File: October 27, 2005 Failing Component:Electrical System Summary:Diagnostic trouble code P0420 may set on low mileage vehicles, or shortly after catalytic converter replacement
TSB Number: 3316 NHTSA Number: 10017210 TSB Date: n/a Date Added to File: October 27, 2005 Failing Component:Electrical System Summary:Diagnostic trouble code P0420 may set on low mileage vehicles, or shortly after catalytic converter replacement
there is a service bulletin for this.

http://www-odi.nhtsa.dot.gov/cars/problems/tsb/results.cfm?start=1&SearchType=DrillDown&type=VEHICLE&year=2005&make=CHEVROLET&model=COBALT&vehtype=PC&typenum=1&component_id=0&summary=true

Aug 02, 2011 | 2006 Chevrolet Cobalt

2 Answers

Engine light stays on, code is p0420 low thresh bank 1.... where is bank 1 located


I'm not sure you understand the difinition of OBD2 fault code P0420, it means that Catalytic converter in the exhaust that is connected to the engine cylinder bank that contains number one engine cylinder has fallen below the a allowed threshold of cleaning pollunts from the engines exhaust stream. I would be more specific but you have not given model or year of the Mercury you have.
Here is the full difinition of OBD2 fault code P0420 from the factory service information system.


P0420 - Catalyst System Efficiency Below Threshold (Bank 1)


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

2 Answers

The vsc light and the trac off light and check engine light all came on at the same time code p0420 comes up on my 2005 highlander what does this mean?


A p0420 sets after Engine and catalyst are warmed up, vehicle driven within set vehicle engine speed range and waveforms of heated O2 sensors bank 1 sensor 1 and bank 1 sensor 2 have the same amplitude.
Catalytic convertor and O2 sensors need to be tested

Apr 24, 2011 | 2005 Toyota Highlander

1 Answer

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.

Aug 24, 2009 | 2002 Toyota Camry

1 Answer

Service engine light comes on , p0420 code


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

Apr 19, 2009 | 2002 Pontiac Firebird

1 Answer

P0420 code shows


P0420 Catalyst System Efficiency Below Threshold (Bank 1)
You have a worn out catalytic converter.

Apr 17, 2009 | 1996 Saturn SL

2 Answers

Engine light on


A code P0420 may mean that one or more of the following has happened:
  • Leaded fuel was used where unleaded was called for
  • An oxygen sensor is not reading (functioning) properly
  • The engine coolant temperature sensor is not working properly
  • Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
  • Retarded spark timing
  • The oxygen sensors in front and behind the converter are reporting too similar of readings
  • That should get you going.

Mar 22, 2009 | 2001 Pontiac Montana

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