I could be wrong, but I don’t think that code will go away unless you can put cats in or perhaps let the secondary sensors ‘think’ the cats are there.

I recall seeing somewhat of a fix, on a Toyota. It involved soldering in a resistor in the signal wire from the rear O2 sensor.


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what are codes set to in the tune? i have a feeling that may be the issue.

 

I'm honestly not sure. I can put the factory cats back in since they're just in a box in the garage.

 

In order for the codes to go away the diagnostic for catalyst efficiency has to run and pass. Hallowed out cats will not help and the diagnostics will keep failing. You need cat light off and hallowed cats will not do that. Get some high flow cats and give it a shot.

 

I have a set of factory cats with their insides I can switch out. There is no CEL, since that was turned off in the tune, but I don't know about clearing those permanent codes.

It'll pass with those codes, after a gazillion drive cycles.

Exactly a gazillion?

 

It'll pass with those codes, after a gazillion drive cycles.

 

The best way to do it is put the stock cats back on activate the CEL and let the system do its thing. It will probably need to run and pass 2-3 key cycles before the permanent codes clear on their own. You cant clear permanent codes with a hand scanner or even HP tuners.

 

It's going to take way more than 2-3 drive cycles to erase a permanent code.

 

The ECM actually watches the upstream and downstream O2s to see that their behavior correlates. I don't remember the exact sequence, but it involves increasing and decreasing the AFR as the car warms up. Upstream O2s see the raw AFR (which is correlated with what the MAF and MAP say there should be). The downstream O2s are expected to show a reduction in O2 compared to the upstream. So if the Cats aren't there, the test will fail because the front and rear O2s always show the same readings. If the O2s aren't there, the test will fail because no O2 sensors also always show the same readings.

You can thank the Feds for imposing restrictions that make it really hard to circumvent the emissions tests. The fact that the car's systems are actually so robust explains why they don't use a tailpipe sniffer to do an inspection, they rely on the ECM. The only way to pass this is to install Cats, get your inspection sticker, and then remove the Cats until next year.

 

I still have factory cats intact, so I can reinstall them.

Out of curiosity, would the "foolers" that keep the downstream sensor out of the flow work?

What I don't understand is how it passed when I had test pipes, but it failed with gutted cats.

 

I had permanent codes disappear eventually with a tune and some time.

Couldn’t tell you the exact process though.

To cheat a down stream O2, you jut need to insulate it with steel wool etc in fresh air and let it show the reduction in reading as explained.

 

Out of curiosity, would the "foolers" that keep the downstream sensor out of the flow work?

I can't honestly say I remember all the details. I had to figure this out on my 02Z06 after I supercharged it. The ECM understands what the Cats are supposed to do. It knows how much O2 is in the exhaust before the Cats. The Cats "catalyze" the oxidation process, without the benefit of flame they get O2 to combine with partially burned and even unburned hydrocarbons in the exhaust. So what comes out the other side of the Cat has to have less O2 than what was going in to the Cat. The ECM varies the mix, intentionally richening and leaning it. It confirms the upstream O2s are working by monitoring the response, and it calculates what the downstream should see and confirms that, too. So a dummy resistive load isn't going to fool the ECM. Like I said, by federal mandate, auto manufacturers have actually made it pretty hard to get around emissions systems. And the proof of how robust those systems are is that State inspections rely on the ECM to say emissions is fine, they don't sniff the tailpipe to see for themselves.

 

I think I'll try a few drive cycles and see if the codes disappear. If worse comes to worse, the cats will have to go back on for a little while.

 

According to an unnamed tuner, the cats need to go back on. The tune has the CEL off, because I installed my own parts, the permanent codes are there. I guess there's a magic spell that I didn't use when installing test pipes to keep the codes from showing. Must've been the Harbor Freight magic wand I was using. As usual, I did get some useful advice from members on here.

 

Just some info on permanent codes:

Permanent codes are a new thing is 2010 and newer vehicles so folks are not up to speed on them yet. With the check engine light off and a permanent code present does not mean there is anything wrong with your car. It means there WAS something wrong with your car and those codes are going to stay around a while to make sure you fixed it right. If not for a CA SMOG you can basically ignore Permanent codes they are not hurting anyone hanging around inside a ECU.

You cannot clear a permanent code with a scanner or battery disconnect.
You can pass a CA SMOG check with a permanent code in place as long as you have these items in place:
No Check Engine Light (meaning no current codes)
Monitors Complete (Except for EVAP, that can be incomplete)
And this is the important part: Driven 200 miles and have 15 Warm Up cycles since the last time the DTC's codes were cleared.

Now doing this 200/15 task will not clear the Permanent code but rather the CA SMOG machine has been programmed to ignore the Permanent code if 200 / 15 is complete.

Warm up cycles are simply the engine getting up to a normal operating temperature then cooling back down below a certain temp. Below is a video of a guy forcing them on a car with a fan to aid in cooling things down. This can be done in your driveway if you want. The standard for most cars is Up to 160 degrees then it wants to see a 40 degree difference. So cold start up to 160 is 1 warm up cycle. Cool Down to 120 and back up to 160 would be #2. But could vary depending on the car.

Most scanners should have the Data PID's that will show you how many warm up cycles you have done and how long you have driven. If those are better than 200/15 you are good to go for a smog. Look in your "DataStream" or "Live Data" list

If you go for the smog and the inspector turns you away because of a permanent code tell them to kindy run your vehicle through the test. It's not thier job to save you from a fail. They are to run the vehicle as it is presented, that is what the BAR tells them.

If they wont give you a test file a complaint with the State BAR and keep trying another place.

File a Complaint

The Bureau of Automotive Repair’s Online Complaint Form...

www.dca.ca.gov

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Thank you for the information, but this thread is 3 years old. Pretty sure he fix his issues.

 

Yea just hoping if new people have a similar problem they come across it. Too many people just keep replacing parts because thier scanner says there is still a code. Hard to get people out of that mindset. Wish they called them some other name besides permanent codes. That freaks people out. A "Repair Verification" code would be a better name for them, too wordy I guess! LOL