Stage 3 Cobb Tune CA Smog Passing

[GreenBeanST]

Hello forums,

I've been having a bit of an issue passing CA smog with the Stage 3 cobb package that was installed on my car when I purchased it. I have replaced the Cobb intake with an OEM intake and brought it back down to a stage 1 tune (staying out of boost to not mess up internals) but I still have a "permanent fault code" of P0420 - Catalyst system efficiency below threshold bank 1 -- on the car when I smog it. I assume this is to do with the downpipe that was installed, I am not sure where to go from here since I am risk of not being able to drive the car again as I am about to pay for the 3rd and final DMV temporary operating permit for the car.

I'm not too mechanically savvy but I need to figure out what I need to do to get the car sorted, has anyone else dealt with this? To be honest I would not have purchased the car if I realized it would be this difficult to make it CA compliant.

 

[FJ16]

Put a stock downpipe back on it.

 

[Dash]

Not quite answering your concerns but I think since mid July, CA Smog techs check for tunes in any car 2000 and newer. They'll fail the car if a tune is detected.

 

[D1JL]

Not quite answering your concerns but I think since mid July CA Smog techs check for tunes in any car 2000 and newer. They'll fail the car if a tune is detected.

This is NOW true.
Use your Cobb AP and reinstall the OEM tune.

Put a stock downpipe back on it.

This is the best solution.
However, putting in a de-follower will remove the P0420 code but it is still illegal and could cause a failure if seen.

 

[Poofies]

You need the stock downpipe and potentially a o2 sensor (your original is likely fine though.) it’s a real bitch to install so good luck.

 

[Dpro]

Two things are possibly wrong with your setup that if corrected would let you pass. First off you need to update the AP to the latest Cobb firmware which will flash into it the California legal COBB OTS tunes . If you flash your car with one of those it will be legal. 2nd is if your downpipe is not stock indeed you need to put a stock downpipe on the car. There are a number of reasons on the downpipe. I know because my Mountune DP would actually work with certain tunes and not trigger codes. Though with my current tune it triggered the same code you have.
Though most likely someone put in a downpipe that would not work with most smog tunes. Most aftermarket ones do not without defoulers and like D1JL said sometimes even that does not work.

 

[Gone in 60]

Curious if your smog tech did any visual inspection before connecting to OBD and getting the P0420, and if so, did he say anything? The downpipe should have been an immediate fail on visual.

As others have said, put a stock DP on it. Learn from my experience, once you do and you clear the code, put quite a few miles on the car to put it through a drive cycle that will cause the ECU to “forget” about the code. I had a P0420 on my very high mileage work van that had a plugged cat. I replaced the cat and O2 sensors, cleared the code, and immediately went for a smog check. I failed because the code was still stored in the ECU. Had to put about 300 miles on it before it would pass.

 

[Gone in 60]

Ha... just jinxed myself. Just jumped in my work van to run some errands, and guess what. My new cat has been cut off. Great!

 

[MikelSS]

Curious if your smog tech did any visual inspection before connecting to OBD and getting the P0420, and if so, did he say anything? The downpipe should have been an immediate fail on visual.

As others have said, put a stock DP on it. Learn from my experience, once you do and you clear the code, put quite a few miles on the car to put it through a drive cycle that will cause the ECU to “forget” about the code. I had a P0420 on my very high mileage work van that had a plugged cat. I replaced the cat and O2 sensors, cleared the code, and immediately went for a smog check. I failed because the code was still stored in the ECU. Had to put about 300 miles on it before it would pass.

I had issues with clearing the P0420 on a previous fiesta as it gets stored as a Permanent Code, and to clear it from the ECU a Universal Test Pattern needs to be done after clearing the code with a scanner:

Turn the ignition ON, start the vehicle and let it idle for at least 30 seconds. Then, without cycling the key, drive the vehicle for at least five minutes at more than 25 mph. Then (again without cycling the key) let the vehicle idle for at least 30 seconds before shutting it OFF. The whole drive cycle must take at least 10 minutes.

What I was doing wrong was not waiting the 30 seconds before shutting the car off.

 

[Gone in 60]

Wow, that's a pretty simple drive cycle. On my Honda van, it's a lot more involved than that.

 

[GreenBeanST]

Thank you for all of the suggestions, this is helpful.

 

[GreenBeanST]

Curious if your smog tech did any visual inspection before connecting to OBD and getting the P0420, and if so, did he say anything? The downpipe should have been an immediate fail on visual.

As others have said, put a stock DP on it. Learn from my experience, once you do and you clear the code, put quite a few miles on the car to put it through a drive cycle that will cause the ECU to “forget” about the code. I had a P0420 on my very high mileage work van that had a plugged cat. I replaced the cat and O2 sensors, cleared the code, and immediately went for a smog check. I failed because the code was still stored in the ECU. Had to put about 300 miles on it before it would pass.

He performed a visual inspection and everything was okay except for the permanent code showing up. It must be the downpipe. Sadly I purchased the car from someone who had the work done at a shop that kept all of the stock parts so I would have to purchase everything, install it then remove the OEM parts and re-install to get back to stage 3.

I have a miata that needs some parts so I'm planning on parting ways with the Fiesta to get that upgraded. If anyone knows someone who would be interested in buying a stage 3 fiesta with recaros and 55k miles feel free to message me.

 

[ToastAutoX]

He performed a visual inspection and everything was okay except for the permanent code showing up. It must be the downpipe. Sadly I purchased the car from someone who had the work done at a shop that kept all of the stock parts so I would have to purchase everything, install it then remove the OEM parts and re-install to get back to stage 3.

I have a miata that needs some parts so I'm planning on parting ways with the Fiesta to get that upgraded. If anyone knows someone who would be interested in buying a stage 3 fiesta with recaros and 55k miles feel free to message me.

You'll have better luck posting a full-on classified in that section of the forums.

Also if you wait long enough, there's the occasional OEM downpipe for sale on here. At least 1 a month from what I see.