Question about Chevrolet Cavalier

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Does any one know normal voltage readings for a 2003 chevy cavalier

I am trying to figure out if i need a new cat or 02 sensors, i have a p0420 code, i have done some research some people say 02 sensor others say cat

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  • tlmcquaid
    tlmcquaid Dec 05, 2012

    there are no exhaust leaks, it has new spark plugs, new oil change, does not consume oil or coolant, i just want to know voltage readings for the 02 sensors to see if mine are working so i dont have to buy a cat

  • Anonymous Dec 05, 2012

    You downstream oxygen sensor works or it wouldn't give you a PO420 Replace the Cat

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  • Chevrolet Master
  • 14,228 Answers

Trouble Code: P0420

Catalyst System Low Efficiency

Possible Causes:


Air leaks at the exhaust manifold or in the exhaust pipesBase engine problems (i.e., high engine oil or coolant usage)Catalytic converter is damaged, contaminated or has failedContinuous engine misfire conditions, or weak or low coil outputFront HO2S or rear HO2S is contaminated with fuel or moistureRear HO2S is loose in the mounting hole (check it for a leak)Front HO2S older (aged) than the rear HO2S (HO2S-12 is lazy)

Posted on Dec 05, 2012

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Posted on Jan 02, 2017

emissionwiz
  • 75117 Answers

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

blueextc3221
  • 15935 Answers

SOURCE: I HAVE A 2003 CHRYSLER 300M SPECIAL WITH 3.5

PLEASE CLICK HERE to see a page dedicated to your Fault Code.

It is Cat. Convertor related.

this is a fault code for a bad drivers side catilist.this code will also set if there is a exhust leak as well on that side.The catilist is covered under warranty for 8 years or 80k

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Posted on Apr 08, 2009

motor1258
  • 6674 Answers

SOURCE: CODE P0420

Check for any exhaust leaks, hopefully your not burning oil, or losing coolant, and have exhaust checked for possible plugged catalytic converter.

Posted on Apr 27, 2009

  • 1071 Answers

SOURCE: I am getting a P0430 and a P0420 code on my 05

there are two more sensors and i would use chrysler sensors

Posted on Jul 21, 2009

CMV9
  • 594 Answers

SOURCE: Pulled code p0420 on 99 chevy astro, 2wd, v6

from what i am finding the code means o2 sensors. they recommend replacing them and if this does not work than replacing the cat converter

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.

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 soloutions

Some suggested steps for troubleshooting a P0420 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.


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Posted on Aug 20, 2009

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1 Answer

I have 2002 chevy impala changed the 02 sensor and it is still reading the same 02 sensor.


because its not the sensor.
its the plug for the sensor .the wires.or it
is the cataletic converter/exhaust system
i just replaced my exhaust on my 07 chevy malibu same o2 sensor issue p0420 or something like that ?!
replace the converter and youll be fine i still have my old sensors in there that gave me the code :)
there not saying there bad but that the cat is bad.

Mar 18, 2015 | 2002 Chevrolet Impala

1 Answer

04 Altima 2.5 s w 150k changed cat 2014 1 yr later p0420 code again what r normal reads for 02 sensors? reads @ idle fluctuate @ .3V b1 sensor & .8V b2 sensor.anyone had p0420 that wasnt a bad cat


Those cars are notorious for engine problems unfortunately. The exhaust valves tend to warp from heat after around 200k miles. Therefore throwing the O2 codes. Best outcome and cost effective thing I can recommend is replacing the engine with a new or low mileage engine.

Feb 18, 2015 | Cars & Trucks

1 Answer

I have a 2003 saturn ion 4 door, it has a ton of miles 194k. Last week the alternator went out do I replaced it without a problem, then the day after the check engine light came on I hook up the diagnostic...


p0420

no FSM> and not looking up P0420?
no engine stated, so ill get it wrong too..?????????????
420 is cat monitor failure. "efficiency"
the most hard of all.

ill make a list from hard and expensive .
1: bad sensor 2 rear. you failed to do both, that was WRONG.
2: bad cat. (i can weld on any cat for $99 bucks.) i do it last.. dead last.
3: engine running real bad. BUY a scan tool, now.

so the o2 is new that leaves #2 or #3.
i never shot gun cats. but shops do, its not their cash, huh?

i connect a real scan tool (not one that misses factory DTC codes)
then look at pendings for P042o , see funny sensor readings there, bingo.
i check every PID. for all sensors to be sure they READ right.
ECT AT 180F+ AND HOLDING? HOT.>?,
is the engine holding closed loop status at idle, no fix that NOW.
is LTFT (long term fuel trim ) near 0 or at - 40 or + 40% (fix that next)
if trim is good, the engine.
If the front 02 is new, the AFR will be correct and the the front 02 will swing fast and the trim will be near 0 , -4 is near best.
tad rich , natural.
once the engine is running Stoich at light flat cruise. (close loop) the
cat will heal its self (bake dry) and stop throwing 420. ( a hope deal)
if not the cat is bad.

ive cured some of the most hard 420s,.

on some ratty engines, a new cat can in fact hide it , until it cooks to death and next year 420 are back.
id never do that because gas is expensive. fix engine first.

Jun 24, 2014 | Cars & Trucks

1 Answer

P0420 Cat prob.or 02 senor


You won't know until you get both components checked out. A mechanic can measure the temp of the exhaust pipe before and after the cat to check it. The O2 sensors would need a scanner.

Jun 27, 2013 | Volkswagen Cars & Trucks

1 Answer

2003 impala. Hard starts and fumes smell.


this is what i found for you

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 sensorwaveform reading should fluctuate. The downstream O2 sensoricon1.png 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.

Most likely, the aftermarket cat they installed is a high flow cat. This commonly causes issues with throwing that code on our cars. You can either have an OE cat installed, or just have the code deleted from the PCM by someone that has a tuner.
Good Luck

Jan 10, 2013 | 2003 Chevrolet Impala

1 Answer

I am a master tech for a gm dealership. I have dealt with many domestic driveability issues, however I drive a 2003 tundra 4.7 v8. While I take some grief from my fellow employee's, I drive the toyota...


#1 When you replace 02 sensors you should always replace all of them. Otherwise the new 02 sensor will be returning its Data back to the computer faster than the other old ones and this in itself may cause problems. #2 the P0420 indicates that the Catalysts System Efficiency is below the threshold on bank #1 And yes put in all new sensors and that means bank 1 sensor #2 as well. And then if the P0420 code returns replace the Catalatic converter on Bank#1.Please let me know the results. Good Luck and have a good XMASS.

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P0430....Catalyst System Efficiency Below Threshold (Bank 2)try changing the O2 sensors the one before the cat is the first one to fail in normal circumstances ,must be an american market model this vehicle as i cannot read a europeon market vehcle here in europe ,encrypted software

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1 Answer

05 Chevy Malibu P0420 code has set the check engine light.


Hi. P0420 is a catalyst efficiency code. 100% of the time you need a new catalytic converter. If you want to be sure it is the cat pull the O2 sensor before the cat and drive it, the sluggishness will go away because there is no more restriction.

Aug 26, 2010 | 2003 Chevrolet Malibu

4 Answers

Would like to check 02 sensor


A scan tool would work better.Then you can monitor the o2 while the vehicle is running.Also check the exhaust system to make sure it is not kinked or the exhaust system is blocked.If it is good then the problem is usually the catalytic converter.Hopoe this helps.Good luck.

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