97 Tahoe w/ 90k miles. Original California Tahoe.... Did a full tune up in August before sending it to Connecticut with my daughter for college. It's been having a P0420 code every 200 miles or so... While there only driven about 200 miles per month and will be there 2 more years. It's California registered. I wanted to know if I could use 49 state cats as replacement? The sales sites all say "cannot ship to California" ... Not that the less expensive cats won't fit... Thoughts? I have to do this remotely with a local (to her) shop... Thanks!
P 0420 Code AGAIN!
- Thread starter msark
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letsbangout
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What if it's not your cat at all?
By that I mean, what if it pops the code as a result of low voltage from the O2 sensor? Mine registers real low voltage and occasionally pops an 0420. Now it could be real in my case because I understand the last owner blew the first engine, then replaced it and blew the head gasket, so it's entirely possible a good quantity of fluid leaked down into the cat and killed it. But yeah, food for thought. Any OBD-II code scanner that can read live data should be able to show you the post-cat O2 sensor voltage; mine is usually around 0.06v whereas it should be about double that. One day soon i'll jack it up and figure out whether that's real, or if it's a problem on the voltage supply, or what.
By that I mean, what if it pops the code as a result of low voltage from the O2 sensor? Mine registers real low voltage and occasionally pops an 0420. Now it could be real in my case because I understand the last owner blew the first engine, then replaced it and blew the head gasket, so it's entirely possible a good quantity of fluid leaked down into the cat and killed it. But yeah, food for thought. Any OBD-II code scanner that can read live data should be able to show you the post-cat O2 sensor voltage; mine is usually around 0.06v whereas it should be about double that. One day soon i'll jack it up and figure out whether that's real, or if it's a problem on the voltage supply, or what.
ch4d
Full Access Member
Some suggested steps for troubleshooting a P0420 error 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.
or what you could do is change the o2 sensor to that has fixed my problem
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.
or what you could do is change the o2 sensor to that has fixed my problem
SunlitComet
OBS Jedi-Do Good
Mark, you will need the Cali cats. The have the compound construction to meet Cali emissions. Btw it is not the low voltage that kicks the p420 code. it is the waveform pattern from it that the computer sees.
