P0420 Fix
Joined: Feb 2017
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From: Čakovec, Croatia
how to measure that?
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I'm sorry to bring this from the dead, but I'm having a similar issue. I replaced my cat with a brand new one from JCWhitney, it was fine for a few months but CEL is back again with the P0420. I took the cat out again, shook it a little, not rattling, everything looks intact, no weird smells either. I tried the spark plug spacer, engine light still won't go away. I don't know what else it could be. Please help!
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From: Long Island, New York
O2 sensor will not fix a P0420.
It is cat operation, that’s it. The 420 signifies that the 02 sensors are just fine.
The JC whitney cat is borderline passing when new. As time goes on, the cat action deteriorates.
An 02 spacer is the answer. If it doesn’t fix the problem, it is drilled too big, or it is too close to the exhaust stream (needs additional spacer)
It is cat operation, that’s it. The 420 signifies that the 02 sensors are just fine.
The JC whitney cat is borderline passing when new. As time goes on, the cat action deteriorates.
An 02 spacer is the answer. If it doesn’t fix the problem, it is drilled too big, or it is too close to the exhaust stream (needs additional spacer)
Last edited by Billman250; Oct 23, 2018 at 08:27 AM.
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It doesn't come back right away...I don't know what the drive cycle that's needed for readiness, but the light usually comes on after like a week of driving (I drive around 15 miles/day).
Also, when the light does come on, it says on for a few days, turns off for a few days, comes back on again. Why would it not just stay on if the cat is bad?
I have a 2008 btw, with 127K miles.
I just need it to pass the darn inspection. Someone suggested to reset the codes, drive it enough to get 3 out of 4 MIL Ready (the 4th MIL not ready being the cat converter) and it'll still pass emission. I will try that.
Also, when the light does come on, it says on for a few days, turns off for a few days, comes back on again. Why would it not just stay on if the cat is bad?
I have a 2008 btw, with 127K miles.
I just need it to pass the darn inspection. Someone suggested to reset the codes, drive it enough to get 3 out of 4 MIL Ready (the 4th MIL not ready being the cat converter) and it'll still pass emission. I will try that.
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Joined: Mar 2011
Posts: 14
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O2 sensor will not fix a P0420.
It is cat operation, that’s it. The 420 signifies that the 02 sensors are just fine.
The JC whitney cat is borderline passing when new. As time goes on, the cat action deteriorates.
An 02 spacer is the answer. If it doesn’t fix the problem, it is drilled too big, or it is too close to the exhaust stream (needs additional spacer)
It is cat operation, that’s it. The 420 signifies that the 02 sensors are just fine.
The JC whitney cat is borderline passing when new. As time goes on, the cat action deteriorates.
An 02 spacer is the answer. If it doesn’t fix the problem, it is drilled too big, or it is too close to the exhaust stream (needs additional spacer)
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From: Long Island, New York
Registered User
Joined: Mar 2011
Posts: 14
Likes: 0
O2 sensor will not fix a P0420.
It is cat operation, that’s it. The 420 signifies that the 02 sensors are just fine.
The JC whitney cat is borderline passing when new. As time goes on, the cat action deteriorates.
An 02 spacer is the answer. If it doesn’t fix the problem, it is drilled too big, or it is too close to the exhaust stream (needs additional spacer)
It is cat operation, that’s it. The 420 signifies that the 02 sensors are just fine.
The JC whitney cat is borderline passing when new. As time goes on, the cat action deteriorates.
An 02 spacer is the answer. If it doesn’t fix the problem, it is drilled too big, or it is too close to the exhaust stream (needs additional spacer)
"Depends on the year.
00-05 you can use spark plug spacers no problem.
06-09 you need a right angle spacer, and point it towards the front of the car."
Mine is an 08..where can I find this "right-angle spacer"?
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ok well I just took it to autozone to pull the codes again..now it's P2270 O2 Sensor Signal Stuck Lean Bank 1 Sensor 2. This is new so I'm wondering if it's because of the 2 non-foulers I have installed there.
And P0420 isn't there anymore, but maybe it'll come back once I address this issue.
And P0420 isn't there anymore, but maybe it'll come back once I address this issue.