Smog Test P0420 Failed - Advice?
#1
Smog Test P0420 Failed - Advice?
I just failed the californian smog test. I've got a high flow cat and the tester told me that he pulled a P0420 during the idle test. Is it possible for a tester to vary AFR during idle, and then observe the difference between O2 sensors before and after the cat? If so is there a way I can run this type of test myself with laptop software, to see if it is the O2 sensors or the cat that needs replacing.
#3
I'm back to stock for the smog test. The only thing non-stock is the HFC. Had no codes indicating cat was finished in the week before. I didn't disable the rear O2 sensor because I think they run some kind of a test from the smog computer to see how it responds. Is there a way for me to simulate the O2 sensor tests that are used to generate a P0420. I want to eliminate the O2 sensors first and that will only leave the cat. If that is the case, I'll just find a stock cat and fit that before the retest.
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#10
I have a 2003 ev 8 and my car keeps popping the P0420 engine code and i've replaced both the rear and the front o2 sensors and the the egr valve, and it's still popping up. Is the anybody out there having the same problem? and what can i do to fix it, it's been on for almost a year and now it's starting to idle down when i come to a stop but comes back up when i stop all the way.
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#14
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Changing a setting in the computer is not going to make the readings from the sniffer any different. Putting back on the stock cat is what's going to allow the car to pass the Two speed idle test that is done on AWD cars in California. Running a HFC/test pipe will show over limit HCs. I have read some cars passing CA emission tests with a HFC, but most will not. Getting rid of a code does not have anything to do with the TSI part of the smog test. Having no pending codes is just part of the whole test.
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#15
Evolved Member
Changing a setting in the computer is not going to make the readings from the sniffer any different. Putting back on the stock cat is what's going to allow the car to pass the Two speed idle test that is done on AWD cars in California. Running a HFC/test pipe will show over limit HCs. I have read some cars passing CA emission tests with a HFC, but most will not. Getting rid of a code does not have anything to do with the TSI part of the smog test. Having no pending codes is just part of the whole test.
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