P0420 CODE HELP!!!
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P0420 CODE HELP!!!
I have a 2007 5.3L Avalanche, bought 3 months ago the repair shop has it more than me..uugh
141,700 miles on it, bought as is( my bad)
Day i took it home check engine light came on
P0420 and p0430 code it won't pass inspection so took it to a mechanic 1st thing he did was a full tune up spark plugs ect.. said that can throw the code..
Code came back ,
2nd time in, found a cheap China y pipe,
So put in a New California emissions Y pipe with new cats, 900. And new 02 sensor on bank 2 sensor 2, still p420 code,.
3rd time back New ECM and programed,
Still p420..
4th time back no answer yet.
On the code reader
Bank 2 sensor 2 looks perfect. .6 volts steady...
Than drops to .01 no volts..
Than up again fluctuating
Than 0 volts for awhile...
Than .6 steady perfect
HELP what can it be
New ecm ,new cats , new 02 sensor
Side note:
Bank 1 sensor 2 always .7 volts steady
So he swapped the sensors
the problem stayed on bank 2
141,700 miles on it, bought as is( my bad)
Day i took it home check engine light came on
P0420 and p0430 code it won't pass inspection so took it to a mechanic 1st thing he did was a full tune up spark plugs ect.. said that can throw the code..
Code came back ,
2nd time in, found a cheap China y pipe,
So put in a New California emissions Y pipe with new cats, 900. And new 02 sensor on bank 2 sensor 2, still p420 code,.
3rd time back New ECM and programed,
Still p420..
4th time back no answer yet.
On the code reader
Bank 2 sensor 2 looks perfect. .6 volts steady...
Than drops to .01 no volts..
Than up again fluctuating
Than 0 volts for awhile...
Than .6 steady perfect
HELP what can it be
New ecm ,new cats , new 02 sensor
Side note:
Bank 1 sensor 2 always .7 volts steady
So he swapped the sensors
the problem stayed on bank 2
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Joined: Feb 2015
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What region does it live in?
What else is included in "etc." ?
What was the condition of the old plugs (please don't just say "they were good") ?
What kind of plugs and what gap was used?
What make and model y-pipe/cats were pulled out?
What make and model y-pipe/cats were put in?
New cats should solve P0420 and P0430 , however, I have seen bad O2 sensors give an erroneous reading that triggers these codes. I am curious why just the one O2 sensor was replaced . . . ? . . . and suggest you replace all of them.
Why?
Has anyone traced all of the wiring from the O2 sensors?
Cheap Chinese y-pipe means someone'* been messing with it. These don't eat themselves easily. This tells me that perhaps it had a programmer in its past or that maybe it had or has one of those cheap power adders that messes with the MAF reading.
I am also concerned with all of the parts swapping going on. Spark plugs might have been a good idea. Oxygen sensors should have all been replaced. Catalytics maybe. PCM? I don't understand that one.
What else is included in "etc." ?
What was the condition of the old plugs (please don't just say "they were good") ?
What kind of plugs and what gap was used?
What make and model y-pipe/cats were put in?
New cats should solve P0420 and P0430 , however, I have seen bad O2 sensors give an erroneous reading that triggers these codes. I am curious why just the one O2 sensor was replaced . . . ? . . . and suggest you replace all of them.
Why?
On the code reader
Bank 2 sensor 2 looks perfect. .6 volts steady...
Than drops to .01 no volts..
Than up again fluctuating
Than 0 volts for awhile...
Than .6 steady perfect
HELP what can it be
New ecm ,new cats , new 02 sensor
Side note:
Bank 1 sensor 2 always .7 volts steady
So he swapped the sensors
the problem stayed on bank 2
Bank 2 sensor 2 looks perfect. .6 volts steady...
Than drops to .01 no volts..
Than up again fluctuating
Than 0 volts for awhile...
Than .6 steady perfect
HELP what can it be
New ecm ,new cats , new 02 sensor
Side note:
Bank 1 sensor 2 always .7 volts steady
So he swapped the sensors
the problem stayed on bank 2
Has anyone traced all of the wiring from the O2 sensors?
Cheap Chinese y-pipe means someone'* been messing with it. These don't eat themselves easily. This tells me that perhaps it had a programmer in its past or that maybe it had or has one of those cheap power adders that messes with the MAF reading.
I am also concerned with all of the parts swapping going on. Spark plugs might have been a good idea. Oxygen sensors should have all been replaced. Catalytics maybe. PCM? I don't understand that one.
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Joined: Dec 2003
Posts: 249
Likes: 43
From: Baldwin,New York
If new cats didn't solve it then you could try Oxygen senor adapters that move the tip of the O2 sensors out of the direct exhaust stream. Do a Google search for O2 eliminators.
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Junior Member
Joined: Oct 2020
Posts: 4
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Reply
What region does it live in?
What else is included in "etc." ?
What was the condition of the old plugs (please don't just say "they were good") ?
What kind of plugs and what gap was used?
What make and model y-pipe/cats were pulled out?
What make and model y-pipe/cats were put in?
New cats should solve P0420 and P0430 , however, I have seen bad O2 sensors give an erroneous reading that triggers these codes. I am curious why just the one O2 sensor was replaced . . . ? . . . and suggest you replace all of them.
Why?
Has anyone traced all of the wiring from the O2 sensors?
Cheap Chinese y-pipe means someone'* been messing with it. These don't eat themselves easily. This tells me that perhaps it had a programmer in its past or that maybe it had or has one of those cheap power adders that messes with the MAF reading.
I am also concerned with all of the parts swapping going on. Spark plugs might have been a good idea. Oxygen sensors should have all been replaced. Catalytics maybe. PCM? I don't understand that one.
What else is included in "etc." ?
What was the condition of the old plugs (please don't just say "they were good") ?
What kind of plugs and what gap was used?
What make and model y-pipe/cats were pulled out?
What make and model y-pipe/cats were put in?
New cats should solve P0420 and P0430 , however, I have seen bad O2 sensors give an erroneous reading that triggers these codes. I am curious why just the one O2 sensor was replaced . . . ? . . . and suggest you replace all of them.
Why?
Has anyone traced all of the wiring from the O2 sensors?
Cheap Chinese y-pipe means someone'* been messing with it. These don't eat themselves easily. This tells me that perhaps it had a programmer in its past or that maybe it had or has one of those cheap power adders that messes with the MAF reading.
I am also concerned with all of the parts swapping going on. Spark plugs might have been a good idea. Oxygen sensors should have all been replaced. Catalytics maybe. PCM? I don't understand that one.
look over the vacuum lines, and a complete look over of the engine,
not sure of the brand of the Y pipe old or new
the new sensor because someone smashed it into an extension to move it out if the exhaust pipe.
they did not open the hole
The PCM because swapping the downstream sensor back and forth problem stayed on bank 2, could be a computer module..
He said he checked the wiring also..
looks perfect
good than drops off
up and down
Thread Starter
Junior Member
Joined: Oct 2020
Posts: 4
Likes: 0
Reply
What region does it live in?
What else is included in "etc." ?
What was the condition of the old plugs (please don't just say "they were good") ?
What kind of plugs and what gap was used?
What make and model y-pipe/cats were pulled out?
What make and model y-pipe/cats were put in?
New cats should solve P0420 and P0430 , however, I have seen bad O2 sensors give an erroneous reading that triggers these codes. I am curious why just the one O2 sensor was replaced . . . ? . . . and suggest you replace all of them.
Why?
Has anyone traced all of the wiring from the O2 sensors?
Cheap Chinese y-pipe means someone'* been messing with it. These don't eat themselves easily. This tells me that perhaps it had a programmer in its past or that maybe it had or has one of those cheap power adders that messes with the MAF reading.
I am also concerned with all of the parts swapping going on. Spark plugs might have been a good idea. Oxygen sensors should have all been replaced. Catalytics maybe. PCM? I don't understand that one.
What else is included in "etc." ?
What was the condition of the old plugs (please don't just say "they were good") ?
What kind of plugs and what gap was used?
What make and model y-pipe/cats were pulled out?
What make and model y-pipe/cats were put in?
New cats should solve P0420 and P0430 , however, I have seen bad O2 sensors give an erroneous reading that triggers these codes. I am curious why just the one O2 sensor was replaced . . . ? . . . and suggest you replace all of them.
Why?
Has anyone traced all of the wiring from the O2 sensors?
Cheap Chinese y-pipe means someone'* been messing with it. These don't eat themselves easily. This tells me that perhaps it had a programmer in its past or that maybe it had or has one of those cheap power adders that messes with the MAF reading.
I am also concerned with all of the parts swapping going on. Spark plugs might have been a good idea. Oxygen sensors should have all been replaced. Catalytics maybe. PCM? I don't understand that one.
look over the vacuum lines, and a complete look over of the engine,
not sure of the brand of the Y pipe old or new
the new sensor because someone smashed it into an extension to move it out if the exhaust pipe.
they did not open the hole
The PCM because swapping the downstream sensor back and forth problem stayed on bank 2, could be a computer module..
He said he checked the wiring also..
looks perfect
good than drops off
up and down
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True Car Nut
Joined: Feb 2015
Posts: 6,851
Likes: 1,015
From: Earth
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