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.

 

Are you tuned? You can either run a mechanical fix on the o2 sensor or simply just have your tuner disable the 420 code.

 

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.

 

My advice is hire Benjamin Franklin as a mediator.

 

Thanks for the advice. Benjamin's price is higher than I had hoped. How can I test the O2 sensors?

 

lol:

And if that doesn't work, bring out his twin brother.


If that doesn't work...

Pistol, trash bag and shovel?

 

the tephra mod eliminates that code - and still leaves the run status moniters in OK mode -- thus you pass.

 

Thanks xRoguex - Tephra mod v.7 will be my new negotiator with CARB. I guess I just need to paste in the XML that exposes the bits that will convince Uncle Sam that my HFC is in fact fully operational. Mr. Franklin is fired

 

I have a buddy here in pa that owns an inspection shop. We spent a good hour playing around with the different codes and settings in ecuflash -- and so far as we could tell NOTHING set off his computer as long as the runtime moniters were set to "ok"

 

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.

 

If you have a HFC or test pipe, you usually will not pass smog. You will need to put the stock CAT back on.

N

 

That, or do the fix that has already been mentioned three times.

 

Hi-Flow cats fromt what I have read arent cali smog legal. The one i bought (magnaflow) said 49state legal. Flashing your ecu would be the easiest IMO.

 

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.

N

 

Well, if they did the sniffer part of the test it must have passed. All the OP reports is failing due to a code.