Question about 2002 Pontiac Grand Prix

1 Answer

Engine code po 420 - 2002 Pontiac Grand Prix

Posted by on

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Top Expert:

    An expert who has finished #1 on the weekly Top 10 Fixya Experts Leaderboard.

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

  • Pontiac Master
  • 5,332 Answers

Thats a code for catalytic converter inefficiency. It usually means the cat is no longer able to process the exhaust gasses going through it and needs to be replaced. GM vehicles in general are no strangers to this happening.

Posted on Oct 17, 2010

6 Suggested Answers

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
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.
goodluck!

Posted on Jan 02, 2017

  • 3600 Answers

SOURCE: PO 420 and PO 455 codes

There are three things that can cause this that is unrelated to the cap, if the valve on the carbon canister is defective it would cause this it would also cause a vacuum leak making the car run lean so check the carbon canister check valve first. Next your EGR valve could be dirty or not functioning, depending on the model and engine size it may have two EGR valves one a mechanical and the other the digital EGR and it to may be dirty, if it's dirty it can be taken apart and cleaned with carburetor cleaner and clean the pintal. And lube the pintal valve. If you’re careful and not tear the gasket you can reuse it. If this does not seam to fix the problem then you have a vacuum leak or the device that pumps pressure into the gas tank may be defective.

Posted on Jun 27, 2009

pal03246
  • 713 Answers

SOURCE: 2002 nissan altima 4 cyl

you need a new catalytic convertor. Its covered under factory warantee for 8 years or 80000 miles.

Posted on Oct 13, 2008

SOURCE: I have a 2007 Pacifica and the check engine light

P0420 is catalytic converter efficiency code. This code usually requires the PCM being reprogrammed or the catalytic converter replaced, sometimes both. How many miles are your pacifica? Emissions control equipment should be covered by an 80k / 8 year warranty.

Posted on Jun 08, 2010

Testimonial: "Sounds like you know alot about cars..."

ZJLimited
  • 17970 Answers

SOURCE: The check engine light comes

OBD Code P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

Symptoms: You will likely not notice any drivability problems, although there may be symptoms.

Causes: 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

Some suggested steps for troubleshooting a P0420 error code include:
* 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

One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.

Hope helps.

Posted on Sep 06, 2010

ZJLimited
  • 17970 Answers

SOURCE: vehicle code PO 420 how

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

Symptoms: You will likely not notice any drivability problems, although there may be symptoms.

Causes: 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

Possible Solutions: Some suggested steps for troubleshooting a P0420 error code include:
* 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

One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. Many manufacturers give a five year, unlimited mileage warranty on these items. It's worth checking into.

Hope this helps (remember to rate and comment this).

Posted on Sep 23, 2010

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

1 Answer

Po 420 ?


Why would you change any items?

Have you not googled the code?

420 & 430 are exhaust converter issues

You change no parts,you check for codes & component
test system faults using the codes, until you find a problem

Sep 12, 2014 | 1998 Chevrolet Astro

1 Answer

Po 420 ?


code p0420 refers to cat converter system, bank 1 efficiency below threshold===causes --cat converter--wiring HO2S sensor 2

check that the cat converter is ok and replace the sensor. ( it is a HO2S sensor which will be different to a O2 sensor so get the right one )

Sep 12, 2014 | 1998 Chevrolet Astro

1 Answer

I have 2 codes PO 300 and PO 420


po300 is a random misfire code(could be egr passages blocked under upper pleinum;plug wires;plugs or coils.PO420 is catalatic converter below threshold(converter has to be replaced)

Jan 02, 2014 | 2001 Pontiac Grand Am SE

1 Answer

What could PO 302, PO 300, PO 105, PO106, PO 110,PO 115& PO 120 CODES Mean on a Toyota Camry 2000 model sedan car?


what engine, what size. that is first question.
misfire, map ,maf, iat, ect,tps and cat fail and low coolant temps.
very odd mix there. did you pull connections, key on???????

it means they all fail a test.
DIY? or just curious?

login to alldata.com
the question is , which is the most important.
all are cept 420, (last that, and bet goes way. later.)

reset the ECU, and see which come back.?
check all fuses.
then post codes that repeat, after fuse checks.

does the engine get fully hot running, 180F minimum?

Nov 27, 2013 | 2000 Toyota Camry

1 Answer

2003 outlander / po 420 catalyst below threshold bank1


year, make, model, engine size?

how many miles?

This codes typically indicates that the catalytic converter is no longer functioning.

Apr 04, 2013 | 2004 Ford Freestar

1 Answer

Engine Light on code PO 420


You Prabably need a new catalytic converter. Very common problem with toyotas. You will need to get a dealer part as the aftermarket converters will put your check engine light on eventually.

Dec 20, 2010 | 2000 Toyota Corolla

1 Answer

How to fix the problem related to engine light on code PO 420 of Toyota corolla 2000, Engine 1.8L - golden03


thats pretty easy you just need the right tools to do it and a catyalic converter just recommend you getting it from the dealer only because the after market will go after a yr or 2.

Dec 20, 2010 | 1996 Honda Accord

Not finding what you are looking for?
2002 Pontiac Grand Prix Logo

Related Topics:

465 people viewed this question

Ask a Question

Usually answered in minutes!

Top Pontiac Experts

yadayada
yadayada

Level 3 Expert

75807 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22133 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

8172 Answers

Are you a Pontiac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...