P0420 code cat clogged
#1
04-18-2017
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P0420 code cat clogged
I have a 03 ranger 3.0L. last week my CEL came on. Ran the codes and bank 2 was rich and misfire on 3,4,&5 cylinders. Replaced the plugs and no CEL but the cat seems to be clogged. I know there is 2 pre cats and 2 post cats. My question is can I cut the actual cat out and replace with pipe and keep the pre and post cats? I live in Virginia so there isn't an emissions test.
#2
04-18-2017
Welcome to the forum
Cat converts are Federally, as well as locally, required
But you "can" do what you want, just legally you "may" not do it.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
This doesn't mean cat converter is clogged although it could be
Starting in 1995/6 an O2 sensor was added after the Cat converters, two O2s on Dual exhausts.
On single exhaust systems(all Rangers) the one O2 sensor is called Bank 1 sensor 2
So it really isn't drivers side or passenger side specific like the Upstream O2s are
P0420 Bank 1 for rear O2 sensor just means whole exhaust system is not cleaning up exhaust like it should be.
If you get a Vacuum gauge you can see if exhaust is clogged with simple test by opening and closing throttle with engine running.
If exhaust system is clogged, or even partially blocked, back pressure will build up as RPMs do, when you release(close) throttle, high vacuum should come back instantly if it is slow to return then exhaust has back pressure building up.
Upstream O2 sensors are used to set air:fuel trims for best running and economy
Computer gets an average between them and then compares that average with the Downstream(rear) O2 sensor's reading
This is what sets P0420, the comparison
Rear O2 should be showing Cleaner exhaust, higher oxygen content, than average from front O2s, than means Cats are working.
What codes, exactly, told you Bank 2 was rich?
(I think you mean 4,5,6 on cylinders numbers, right?)
And when you pulled out the old spark plugs were they Blackish, showing true Rich running?
Rich running can Foul upstream O2 sensors, upstream O2 sensors have a life expectancy of about 100K miles, you will usually notice MPG slowly dropping as upstream O2 starts to fail
Downstream O2's usually last 3 or 4 times as long as upstream because they "see' cleaner exhaust.
A single bank on a V6 engine running rich could be failed O2 but you would probably get a "switching" code, but not always.
Could also be leaking fuel injector
Or yes, a clogged cat on that bank
Cat converts are Federally, as well as locally, required
But you "can" do what you want, just legally you "may" not do it.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
This doesn't mean cat converter is clogged although it could be
Starting in 1995/6 an O2 sensor was added after the Cat converters, two O2s on Dual exhausts.
On single exhaust systems(all Rangers) the one O2 sensor is called Bank 1 sensor 2
So it really isn't drivers side or passenger side specific like the Upstream O2s are
P0420 Bank 1 for rear O2 sensor just means whole exhaust system is not cleaning up exhaust like it should be.
If you get a Vacuum gauge you can see if exhaust is clogged with simple test by opening and closing throttle with engine running.
If exhaust system is clogged, or even partially blocked, back pressure will build up as RPMs do, when you release(close) throttle, high vacuum should come back instantly if it is slow to return then exhaust has back pressure building up.
Upstream O2 sensors are used to set air:fuel trims for best running and economy
Computer gets an average between them and then compares that average with the Downstream(rear) O2 sensor's reading
This is what sets P0420, the comparison
Rear O2 should be showing Cleaner exhaust, higher oxygen content, than average from front O2s, than means Cats are working.
What codes, exactly, told you Bank 2 was rich?
(I think you mean 4,5,6 on cylinders numbers, right?)
And when you pulled out the old spark plugs were they Blackish, showing true Rich running?
Rich running can Foul upstream O2 sensors, upstream O2 sensors have a life expectancy of about 100K miles, you will usually notice MPG slowly dropping as upstream O2 starts to fail
Downstream O2's usually last 3 or 4 times as long as upstream because they "see' cleaner exhaust.
A single bank on a V6 engine running rich could be failed O2 but you would probably get a "switching" code, but not always.
Could also be leaking fuel injector
Or yes, a clogged cat on that bank
#3
04-18-2017
Join Date: Apr 2017
Location: Roanoke
Posts: 5
Likes: 0
Received 0 Likes
on
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Welcome to the forum
Cat converts are Federally, as well as locally, required
But you "can" do what you want, just legally you "may" not do it.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
This doesn't mean cat converter is clogged although it could be
Starting in 1995/6 an O2 sensor was added after the Cat converters, two O2s on Dual exhausts.
On single exhaust systems(all Rangers) the one O2 sensor is called Bank 1 sensor 2
So it really isn't drivers side or passenger side specific like the Upstream O2s are
P0420 Bank 1 for rear O2 sensor just means whole exhaust system is not cleaning up exhaust like it should be.
If you get a Vacuum gauge you can see if exhaust is clogged with simple test by opening and closing throttle with engine running.
If exhaust system is clogged, or even partially blocked, back pressure will build up as RPMs do, when you release(close) throttle, high vacuum should come back instantly if it is slow to return then exhaust has back pressure building up.
Upstream O2 sensors are used to set air:fuel trims for best running and economy
Computer gets an average between them and then compares that average with the Downstream(rear) O2 sensor's reading
This is what sets P0420, the comparison
Rear O2 should be showing Cleaner exhaust, higher oxygen content, than average from front O2s, than means Cats are working.
What codes, exactly, told you Bank 2 was rich?
(I think you mean 4,5,6 on cylinders numbers, right?)
And when you pulled out the old spark plugs were they Blackish, showing true Rich running?
Rich running can Foul upstream O2 sensors, upstream O2 sensors have a life expectancy of about 100K miles, you will usually notice MPG slowly dropping as upstream O2 starts to fail
Downstream O2's usually last 3 or 4 times as long as upstream because they "see' cleaner exhaust.
A single bank on a V6 engine running rich could be failed O2 but you would probably get a "switching" code, but not always.
Could also be leaking fuel injector
Or yes, a clogged cat on that bank
Cat converts are Federally, as well as locally, required
But you "can" do what you want, just legally you "may" not do it.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
This doesn't mean cat converter is clogged although it could be
Starting in 1995/6 an O2 sensor was added after the Cat converters, two O2s on Dual exhausts.
On single exhaust systems(all Rangers) the one O2 sensor is called Bank 1 sensor 2
So it really isn't drivers side or passenger side specific like the Upstream O2s are
P0420 Bank 1 for rear O2 sensor just means whole exhaust system is not cleaning up exhaust like it should be.
If you get a Vacuum gauge you can see if exhaust is clogged with simple test by opening and closing throttle with engine running.
If exhaust system is clogged, or even partially blocked, back pressure will build up as RPMs do, when you release(close) throttle, high vacuum should come back instantly if it is slow to return then exhaust has back pressure building up.
Upstream O2 sensors are used to set air:fuel trims for best running and economy
Computer gets an average between them and then compares that average with the Downstream(rear) O2 sensor's reading
This is what sets P0420, the comparison
Rear O2 should be showing Cleaner exhaust, higher oxygen content, than average from front O2s, than means Cats are working.
What codes, exactly, told you Bank 2 was rich?
(I think you mean 4,5,6 on cylinders numbers, right?)
And when you pulled out the old spark plugs were they Blackish, showing true Rich running?
Rich running can Foul upstream O2 sensors, upstream O2 sensors have a life expectancy of about 100K miles, you will usually notice MPG slowly dropping as upstream O2 starts to fail
Downstream O2's usually last 3 or 4 times as long as upstream because they "see' cleaner exhaust.
A single bank on a V6 engine running rich could be failed O2 but you would probably get a "switching" code, but not always.
Could also be leaking fuel injector
Or yes, a clogged cat on that bank
#4
04-18-2017
So you lose power above 3,000 RPM, that would certainly be consistent with clogged exhaust or fuel pressure issue
And spark plugs in 1,2 and 3 looked OK?
Eaten away tips reads like false Lean issue, cylinder is running hotter than it should.
And there was no Pinging noise associated with poor engine performance?
Rich running will get carbon build up, blackish residue, but that could have started after misfires started from tips wearing down.
But any of this could have caused cats to overheat and start breaking apart internally.
Just looking down the road after you remove or replace the Cats to see what caused the Cats to fail if they have.
Generally speaking Cats don't just fail, there is a cause that shortens their lives
And spark plugs in 1,2 and 3 looked OK?
Eaten away tips reads like false Lean issue, cylinder is running hotter than it should.
And there was no Pinging noise associated with poor engine performance?
Rich running will get carbon build up, blackish residue, but that could have started after misfires started from tips wearing down.
But any of this could have caused cats to overheat and start breaking apart internally.
Just looking down the road after you remove or replace the Cats to see what caused the Cats to fail if they have.
Generally speaking Cats don't just fail, there is a cause that shortens their lives
#5
04-18-2017
Join Date: Apr 2017
Location: Roanoke
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
Welcome to the forum
Cat converts are Federally, as well as locally, required
But you "can" do what you want, just legally you "may" not do it.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
This doesn't mean cat converter is clogged although it could be
Starting in 1995/6 an O2 sensor was added after the Cat converters, two O2s on Dual exhausts.
On single exhaust systems(all Rangers) the one O2 sensor is called Bank 1 sensor 2
So it really isn't drivers side or passenger side specific like the Upstream O2s are
P0420 Bank 1 for rear O2 sensor just means whole exhaust system is not cleaning up exhaust like it should be.
If you get a Vacuum gauge you can see if exhaust is clogged with simple test by opening and closing throttle with engine running.
If exhaust system is clogged, or even partially blocked, back pressure will build up as RPMs do, when you release(close) throttle, high vacuum should come back instantly if it is slow to return then exhaust has back pressure building up.
Upstream O2 sensors are used to set air:fuel trims for best running and economy
Computer gets an average between them and then compares that average with the Downstream(rear) O2 sensor's reading
This is what sets P0420, the comparison
Rear O2 should be showing Cleaner exhaust, higher oxygen content, than average from front O2s, than means Cats are working.
What codes, exactly, told you Bank 2 was rich?
(I think you mean 4,5,6 on cylinders numbers, right?)
And when you pulled out the old spark plugs were they Blackish, showing true Rich running?
Rich running can Foul upstream O2 sensors, upstream O2 sensors have a life expectancy of about 100K miles, you will usually notice MPG slowly dropping as upstream O2 starts to fail
Downstream O2's usually last 3 or 4 times as long as upstream because they "see' cleaner exhaust.
A single bank on a V6 engine running rich could be failed O2 but you would probably get a "switching" code, but not always.
Could also be leaking fuel injector
Or yes, a clogged cat on that bank
Cat converts are Federally, as well as locally, required
But you "can" do what you want, just legally you "may" not do it.
P0420 - Catalyst System Efficiency Below Threshold (Bank 1)
This doesn't mean cat converter is clogged although it could be
Starting in 1995/6 an O2 sensor was added after the Cat converters, two O2s on Dual exhausts.
On single exhaust systems(all Rangers) the one O2 sensor is called Bank 1 sensor 2
So it really isn't drivers side or passenger side specific like the Upstream O2s are
P0420 Bank 1 for rear O2 sensor just means whole exhaust system is not cleaning up exhaust like it should be.
If you get a Vacuum gauge you can see if exhaust is clogged with simple test by opening and closing throttle with engine running.
If exhaust system is clogged, or even partially blocked, back pressure will build up as RPMs do, when you release(close) throttle, high vacuum should come back instantly if it is slow to return then exhaust has back pressure building up.
Upstream O2 sensors are used to set air:fuel trims for best running and economy
Computer gets an average between them and then compares that average with the Downstream(rear) O2 sensor's reading
This is what sets P0420, the comparison
Rear O2 should be showing Cleaner exhaust, higher oxygen content, than average from front O2s, than means Cats are working.
What codes, exactly, told you Bank 2 was rich?
(I think you mean 4,5,6 on cylinders numbers, right?)
And when you pulled out the old spark plugs were they Blackish, showing true Rich running?
Rich running can Foul upstream O2 sensors, upstream O2 sensors have a life expectancy of about 100K miles, you will usually notice MPG slowly dropping as upstream O2 starts to fail
Downstream O2's usually last 3 or 4 times as long as upstream because they "see' cleaner exhaust.
A single bank on a V6 engine running rich could be failed O2 but you would probably get a "switching" code, but not always.
Could also be leaking fuel injector
Or yes, a clogged cat on that bank
So you lose power above 3,000 RPM, that would certainly be consistent with clogged exhaust or fuel pressure issue
And spark plugs in 1,2 and 3 looked OK?
Eaten away tips reads like false Lean issue, cylinder is running hotter than it should.
And there was no Pinging noise associated with poor engine performance?
Rich running will get carbon build up, blackish residue, but that could have started after misfires started from tips wearing down.
But any of this could have caused cats to overheat and start breaking apart internally.
Just looking down the road after you remove or replace the Cats to see what caused the Cats to fail if they have.
Generally speaking Cats don't just fail, there is a cause that shortens their lives
And spark plugs in 1,2 and 3 looked OK?
Eaten away tips reads like false Lean issue, cylinder is running hotter than it should.
And there was no Pinging noise associated with poor engine performance?
Rich running will get carbon build up, blackish residue, but that could have started after misfires started from tips wearing down.
But any of this could have caused cats to overheat and start breaking apart internally.
Just looking down the road after you remove or replace the Cats to see what caused the Cats to fail if they have.
Generally speaking Cats don't just fail, there is a cause that shortens their lives
So could a bad o2 sensor cause the back pressure issue. If I let off the gas the back pressure goes away and hear like a womp womp sound from the cat. Not pre cat or post cat
#6
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#7
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#8
04-18-2017
No, failing O2 sensor couldn't cause back pressure, but could cause cat to break apart and get clogged up, so if you replaced a cat converter it could fail if O2 was bad and not replaced.
Only test I know of for clogged exhaust is with a Vacuum gauge, and it won't tell you where the clog is, just that there is a clog.
Noises are too subjective to give any clue for this type of problem, the fact it is making a noise that is different means there is a problem, just can't be specific as to the cause of it.
Only test I know of for clogged exhaust is with a Vacuum gauge, and it won't tell you where the clog is, just that there is a clog.
Noises are too subjective to give any clue for this type of problem, the fact it is making a noise that is different means there is a problem, just can't be specific as to the cause of it.
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