code po420 anybody got answer
#1
09-24-05, 04:39 PM
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code po420 anybody got answer
have a 98 chevy silverado 4x4 anybody know what this code means po420 catalst system below threshold left bank dont really know what that is. i was thinking oxygen sensor but the book list 22 seperate codes for the oxygen sensor thier is 4 oxygen sensors on truk 2 on each side.any help appreciated ty sledge 312000 miles on truck
Last edited by SLEDGEHAMMER; 09-24-05 at 04:58 PM.
#2
09-24-05, 05:29 PM
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It means the cat is not working.
Could be anything that effects the fuel/air mixture. Could be as simple as a dirty air filter. Could be the o2 sensor before that cat, Dirty fuel injectors, dirty mass air sensor etc.
It will not be the sensor after the cat. How that code is set is if the after sensor mimics the before sensor it shows the cat is not performing
Could be anything that effects the fuel/air mixture. Could be as simple as a dirty air filter. Could be the o2 sensor before that cat, Dirty fuel injectors, dirty mass air sensor etc.
It will not be the sensor after the cat. How that code is set is if the after sensor mimics the before sensor it shows the cat is not performing
#3
09-25-05, 02:08 PM
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ty for info
thanks for info i checked maf sensor it looked clean filter was a little dirty got some fuel injector cleaner in tank truk doesnt have hesitation any more will see if light reappaers or not i also have a 89 corrola with 260000 miles best car i ever had no problems except basics brakes exhaust ect. my next vehichle will be a used tacoma with a 4 cylinder with gas prices i think thats all i will ever buy again i the big 4 ty for info sledge
#4
09-25-05, 05:54 PM
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Just to clarify, the poor A/F mixture, etc is the root cause. Correcting that may bring the cat back….if not it needs to be replaced.
#5
09-26-05, 10:14 AM
code 420
I had the some code on my little ford. I drove the thing for months like it untill the exhaust line broke off on the front of the CAT. I don't know if the cat was plugged and the extra weight did it in but once I put on the aftermarket cat the code cleared itself and has stayed away.
Nifty
Nifty
#6
10-15-05, 05:32 PM
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code 420 any help apprcieated
code po 420 showing up on scan 2 converters on truck 98 silverado 4x4 1500 5.7 315000 miles truck runs good no problems just service engine soon light comeing on showing po 420 im pretty sure from what ive been told that sensors have thier own codes so is it looking like converters are bad? any help apprciated ty sledge
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10-15-05, 05:47 PM
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#8
10-15-05, 05:52 PM
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converter
i think thats probbally the problem nifty ive tried other things and code keeps comeing up converters will be next is thier any test that can be ran to check them ty sledge
#9
10-15-05, 05:56 PM
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toyotaman
sorry man just trying to figure this out wont post anymore until i learn more about computers and this site sledge
#10
10-15-05, 06:00 PM
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#11
10-18-05, 02:39 PM
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converter repl.
thanks for info thats what i am going to do now .will it hurt motor to drive it like it is until i get them replaced. i plan on getting it done in next month or so . ty guys sledge
#12
06-07-09, 08:51 AM
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Well I have a 1996 Chevy that is getting the same code. I have changed all 4 O2 sensors and both cats and still get the code I do hear an exhaust leak and am going to fix that next since it would through the sensing out of wack. 
