Question about 2002 Pontiac Grand Prix

Open Question

Changed cc converter,front n back oxygen sensors,new egr valve,new plugswires,check engine light comes on,have code reader says po 420?

Posted by on

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

emissionwiz
  • 75797 Answers

SOURCE: Service engine light comes on

This GM's definition of this code:
P1404 - Exhaust Gas Recirculation (EGR) Closed Position Performance
The most common reasons are either the EGR valve position sensor is defective, or the EGR valve is not fully closed due to carbon.

Posted on Dec 23, 2008

  • 295 Answers

SOURCE: Codes: PO133 02, P1133 H 025, P1134 H 025

I would try to clean out the egr valve , check for leaks at the evap canister, check the evap canister soleniod , and lastly change out the cat convertor, The cat convertor is most likely under the federal emmission warranty of 8 yrs,.80000 miles. You can take the vehicle in to have checked by local dealer or call gm customer service to check the warranty on the cat. convertor by giving them your vehicle number.

Posted on Apr 18, 2009

  • 14036 Answers

SOURCE: my 1994 firebird with a 3.4L check engine light

REMOVE EGR VALVE CLEAN OUT THE CARBON INSIDE THE EGR VALVE PORT HOLE IN THE INTAKE MANIFOLD WHERE EGR VALVE SITS.CAREFULLY USE A PIECE OF CLOTHES RACK OR A TINY SCREW DRIVER CLEAN CARBON OUT ROUND HOLE.USE A SHOP VAC TO VACUUM UP THE DEBRIS TO KEEP FROM GETTING INSIDE INTAKE.DONT USE SHOP VAC IF YOU HAVE ANY FUEL LEAKS OR SMELL GAS FUMES UNDER THE HOOD.

Posted on Oct 31, 2010

Testimonial: "thanks will give it a try."

  • 1 Answer

SOURCE: my 2001 bonneville ssei won't stay running i'v

My 2000 Bonneville did the exact same thing. It's the mass flow air sensor I'm almost 100% sure this is what your problem is.

Posted on Dec 30, 2010

  • 252 Answers

SOURCE: The check engine light came

My first thought would be the converter considering the codes....which will cause the sensors/heaters and other components to fail or read as being bad... I would call a dealer and make sure there are no recalls on the emissions systems and anything to do with the vehicle..
Also it would be worth your while to scan it with a TECH 2 scanner......You may have one I dont know......But I worked for Buick/Pontiac/GMC for 5 years and TECH 2 was a life saver...
It will tell you everything !! If it is running fine though I would just change the oxygen sensor,
clear the codes,test drive it then check it again.....But if you have no problem with it and hooked it to an emissions analyzer and it showed ok I wouldnt worry....

Posted on Mar 02, 2011

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 ?


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

2 Answers

EGR Valve keeps blowing out and no power


EGR valve blow-out can be caused by a clogged catalytic converter. A clogged cat. converter will cause pressure to back up in the engine. A test to perform is remove the front oxygen sensor from the exhaust to see if the engine runs better. Removing the oxygen sensor will relieve the pressure if, in fact the cat. converter is clogged. Another cause for EGR blow-out could be that the timing has jumped.The timing can be checked to diagnose this issue.

Mar 28, 2014 | 2003 Mazda Tribute

3 Answers

01 odyssey p0401, p0420, p0401 and tcs light on


Hi there:

DTC P0401 - Insufficient EGR Flow
EGR stands for Exhaust Gas Recirculation. It is part of the vehicle emmissions system, and is used to reduce combustion temperature and pressure to control Oxides of Nitrogen. There are generally three parts to the EGR system: the EGR valve, an actuator solenoid, and a differential pressure sensor EGR (DPFE). These things work together to deliver the correct amount of recirculation based on engine temperature, load, etc. The P0401 code means that OBD detected an insufficient amount of EGR.

Symptoms
You may notice drivability problems such as pinging (a.k.a. pre-ignition knock) when the engine is under load or the vehicle is at higher speeds. There may also be other symptoms.

A code P0401 most likely means one or more of the following has happened:
The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
There is a blockage in the EGR (tube), most likely carbon buildup
The EGR valve is faulty
The EGR valve may not be opening due to a lack of vaccuum

Possible Solutions:
In fixing this code, it is quite common for people to just replace the EGR valve only to have the OBD code return. The EGR valve is not always the culprit.

Use a vacuum pump and pull the EGR valve open while monitoring engine RPM's & DPFE voltage. There should be a noticable difference in RPM's with the EGR open
Clean out the EGR valve and/or tubing to remove deposits
Check the voltage at the DPFE, compare to specified values (refer to a repair manual for your specific model)
Replace the DPFE sensor (with a good quality / OEM one)
Replace the EGR valve


DTC 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: The main symptom to the driver is the illumination of the MIL (malfunction indicator lamp). You will likely not notice any drivability problems, although there may be symptoms. For example, if the substance inside the catalytic converter is broken or failed, it may be restricting the exhaust which will result in a feeling of reduced power output from the vehicle.

A code P0420 may mean that one or more of the following has happened:
Leaded fuel was used where unleaded was called for
A damaged or failed oxygen sensor (HO2S)
Downstream oxygen sensor (HO2S) wiring damaged or connected improperly
The engine coolant temperature sensor is not working properly
Damaged or leaking exhaust manifold / catalytic converter / muffler / exhaust pipe
******** spark timing
The oxygen sensors in front and behind the converter are reporting too similar of readings
Leaking fuel injector or high fuel pressure
Cylinder misfire
Oil contamination

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 (HO2S), replace if necessary
Replace the catalytic converter

Overall probably the biggest mistake vehicles owners make when they have a P0420 code is to simply replace an oxygen sensor (H02S). It is important to do proper diagnosis so you're not wasting money replacing parts unnecessarily.

We strongly recommend that if you need to replace the catalytic converter that you replace it with an OEM unit. Second choice would be a high-quality replacement part. There are many stories in our forums where folks replaced the cat with a cheaper aftermarket one only to have the code return shortly thereafter.

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; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Jun 28, 2012 | Honda Odyssey Cars & Trucks

1 Answer

I have a po 420 sensor how can I fix it


this obd2 trouble code table can help you understand the meaning of code, for po420, you can try:
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.

Sep 06, 2011 | 2000 Toyota Celica

1 Answer

My 2006 chevy aveo displaying check engine light. error code is po 420 "catalyst system efficiency is below threshhold". i took it to my local mechanic and he changed the electric coil wiring....


Oh My God. Talk to an honest mechanic! You probably have a bad oxygen sensor. It will cost you about $45 dollars for a new one. You can change it yourself. It is the oxygen sensor that is located just to the rear of the catalytic converter. replace it and have the codes cleared at an auto parts store. If the code comes back, then you may need to replace the oxygen sensor that is on the engine exhaust. An auto parts store can look at the voltage of each oxygen sensor and tell you which one is bad. Each oxygen sensor should be bouncing around on the voltage and should frequently be at around .7 volts. If one of them is at .1 or .2 volts, that is the bad one. Buy that one and replace it. Very simple. DO NOT DO THE $1400 repair. That repair shop is trying to take you. Hope this helps.

Mar 19, 2017 | 2006 Chevrolet Aveo

2 Answers

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


Code PO 420 is telling you that the Catalyst System Efficiency Below Threshold (Bank 1), so the Cat converter inst working as it should according the the vehicles computer. This can be caused from the converter going bad from age and use. Or it can also mean you have a failing rear oxygen sensor, because this sensor is instrumental in keeping track of what the converter is doing. If the car is driven on several short trips, and hardly ever driven on the highway, you may be able to burn the deposits out of the converter and restore its function. To do this you should drive it on the highway for at least two hours. After this have the light reset. If the code comes back then have the converter and oxygen sensor tested. Most shops will simply want to replace them and see if it fixes the problem. Don't fall for this, because it is expensive, and you don't need them changed unless they are bad. Get the converter tested and the oxygen sensor tested prior to replacement. The problem could be as simple as a bad electrical connection on the oxygen sensor, that is why I say have them tested.

Dec 20, 2010 | 2000 Toyota Corolla

1 Answer

Vehicle code PO 420 how would i repair this.


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).

Sep 23, 2010 | Ford Explorer Cars & Trucks

2 Answers

My daughter has a 02 Ford Taurus and the engine light came on. We were told the problem code was a 420 but they could not diagnose the problem. They turned the light off but soon it came back on. Any...


What was the letter in front of the 0420 (i.e. P or B) if it was a P then the code is for a catalytic effenciency code. this usually caused by a lazy or an O2 sensor that is going out, or the catalytic converter itself is going out. The only way to really find the problem is to hook it up to a diagnostic code reader and monitor the O2 sensors for their flucuations and see if one is not lazy or not reading at all, if the sensors are flucuating then i would lean towards a catalytic converter. Hope this helps you out.

Oct 20, 2009 | 2002 Ford Taurus

1 Answer

I have a 2001 nissan sentra xe and my check engine light is on i had a diagnostic test and the codes PO 455 and PO 0440 came back what does this mean?


PO 455- Evaporative emission control System leak detected (check exhaust system, egr valve, or entire intake and exhaust system)


PO440- Evaporative Emission System Malfunction (also check oxygen sensor)

Jul 13, 2009 | 2001 Nissan Sentra

2 Answers

Showing PO420 and PO304 code


MAP sensor, Maybe, but doubt it.

When the misfire monitor detects a misfire, it will trigger the check engine light with the specific cylinder number as the last digit in the P030X code. For instance cylinder 1 misfire is P0301, cylinder 2 is P0302 etc. In this case we are left with a P0304 in the computer memory. Which is cylinder 4.
Possible Causes:

Fuel injectors, related wiring, sensors and computer issues
Running out of gas, or poor fuel quality
Evaporative emissions system (EVAP) concerns: fuel vapors leaking into engine
Incorrect Fuel Pressure
EGR system concerns: leaking EGR valve or restricted ports
Base engine concerns: low compression, valve train problems and timing issues
Ignition system concerns including, but not limited to:
Faulty spark plugs
Faulty coil or related wiring
Ignition module or related wiring issues
Ignition related sensor faults or wiring issues
This maybe causing PO420 code to go off.
Which is:
P0420 Catalyst System Efficiency Below Threshold (Bank 1)

There is one O2 (oxygen) sensor in front of the catalytic converter (called upstream), and one behind it (downstream). When the engine is warmed up and running normally the upstream oxygen sensor reading fluctuates and the downstream one is fairly steady. In the case where both readings are fairly steady, a P0420 check engine light code is set.

Possible Causes:

Oxygen (O2) sensor not working correctly
Damaged or leaking exhuast (pipe, manifold, catalytic converter)
Damaged catalytic converter

Mar 24, 2009 | 2003 Pontiac Grand Am

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

Related Topics:

158 people viewed this question

Ask a Question

Usually answered in minutes!

Top Pontiac Experts

yadayada
yadayada

Level 3 Expert

75797 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22114 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

8140 Answers

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

Answer questions

Manuals & User Guides

Loading...