Question about 1999 Buick Century

1 Answer

P0420 code what is it &how to fiw - 1999 Buick Century

Posted by on

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Superstar:

    An expert that got 20 achievements.

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

  • Buick Master
  • 17,970 Answers

The DTC P0420 is refer to the 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 helps (remember to rate and comment this answer).

Posted on Apr 04, 2011

1 Suggested Answer

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

Add Your Answer

Uploading: 0%

my-video-file.mp4

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

×

Loading...
Loading...

Related Questions:

1 Answer

Codes po303, po171, po137. po420


2000 Toyota Corolla, P0171 & P0420 codes - YouTube

? 5:43
https://www.youtube.com/watch?v=ahJnJ19-vwY
Jun 13, 2011 - Uploaded by StandardBrandParts
Standard Motor Products presents: Technician's Toolbox "2000Toyota Corolla, P0171 & P0420 codes"

Smoke testing for codes P0171 P0174 - YouTube

? 5:48
https://www.youtube.com/watch?v=kZsqEfP-5zM
Jan 18, 2011 - Uploaded by realfixesrealfast
These two codes mean a V style engine is running lean on both banks. So you have to be thinking - what can ...

How to repair fault code P0171 and reset warning light ...

? 26:31
https://www.youtube.com/watch?v=Y8FBGrCT3rM
Nov 27, 2014 - Uploaded by Peter Finn
How to repair and fix fault or error code P0171 and reset warning light Toyota Corolla VVT-i engine. ... Also how to find fault codeusing OBD scanner. ... Trouble shooting a misfire, Code P0300, P0301, P0302, P0303, P0304, P0305, P0306, ... 2000 Toyota Corolla, P0171 & P0420 codes - Duration: 5:43. by ...


Dec 02, 2015 | 2005 Toyota Corolla

2 Answers

My 2006 chevy malibu doesn't want to shift gears codes P0121 & P0101 & P0420 transmission place said it's not the transmission.


P0101....Mass or Volume Air Flow Circuit Range/Performance Problem
P0121 - Throttle Position Sensor/Switch A Circuit Range/Performance Problem.
P0420 - Catalyst System Low Efficiency
there is criteria that enable trans shift
solve codes problems then transmission will shift normaly

Dec 14, 2014 | 2006 Chevrolet Malibu

1 Answer

P0420 p0171


P0420 (emission) possibe o2 sensor, bad catalitic converter, exhaust leak, cool temp sensor, misfire etc...P0171 = too lean (not get enough fuel) poss cause air flow sensor which is normally on the air intake tube this can also cause the other fault. You first need to check the clamps are tight on the air intake tube yu replaced. then spray aerostart around intake tube & listen for change of revs. also listen for any sucking noise around motor (Vacume leak) if think detected spray aerostart around that area to see if revs change.

Jun 25, 2012 | 2000 Mazda Protege

1 Answer

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

Getting P0420 code & P0303 code...why?


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 SolutionsSome 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

Code p0303 means one cyliner is misfireing. Check spark plugs and wiring cables. If one cylinder isn't working good that could be the possible couse for the first code P0420 and all other engine problems.

Feb 25, 2011 | 2005 Isuzu Ascender

1 Answer

Check engine light p0300, p0420 & mtv solenoid makes noise


P0300
1.ignition system fault spark plug ign wire coil.
2.vacuum leak, inj fault.
3.high or low fuel pressure.
P0420
1.catylist eff low bank1- cat can be defective.
2.eng misfire, vacuum leak.
3.engine oil leak into the exhaust valve guide seals.
as for the warranty i dont know.

May 04, 2010 | 2005 Chrysler Pacifica

1 Answer

Engine codes p1518, p0125, and p0420 for 2001 firebird


P0125 sets when engine coolant temp does not reach temperature for closed loop operation within a set amount of time.
May be a faulty sensor or thermostat.
P0420 Is related to a faulty rear 02sensor.
P1518 PCM & TAC module communication detected missing or invalid serial data.
If TAC related repair has been done, clear DTC & recheck system. It may be necessary to preform clear codes function twice to clear this DTC.
make sure starting system & charging system are functioning properly. Low voltage can cause this DTC to set. This should help. Let me know how its going.

Apr 11, 2010 | 2001 Pontiac Firebird

1 Answer

We have a 1998 Ford f150 WITH code p0420 which has something to do with cadilitic converter we think any ideas as to how to fiw or disconnect fault light? glthomasj@yahoo.com


P0420 tells me that the cataylatic converter is not working need to monitor the o2 sensors with a scanner to check reading and verify converter operation

Mar 31, 2010 | 1998 Ford F150 Regular Cab

2 Answers

P0420 & P0430 codes 99 silverado


codes p0420 and p0430 are both post o2 sensors, the ones after the convertor, both sides if replacing

May 17, 2009 | 1999 Chevrolet Silverado 1500

3 Answers

P0420 and P0430


P0420 and P0430 are codes related to the catalytic converter effeciency. The catalyst will need to be replaced $$.

May 19, 2008 | 2000 Nissan Maxima

Not finding what you are looking for?
1999 Buick Century Logo

673 people viewed this question

Ask a Question

Usually answered in minutes!

Top Buick Experts

yadayada
yadayada

Level 3 Expert

74945 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22095 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

7697 Answers

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

Answer questions

Manuals & User Guides

Loading...