Failed smog due to Permanent DTC. How do I clear it?

[Audibellybutton]

I just failed CA smog because apparently my ecu is storing a permanent dtc for the thermostat that I just repaired a couple weeks ago. There is no CEL on the dash and I cleared the code in VCDS it does not show up in VCDS anymore.

How do I get rid of the code?

The car passed all other emissions and visual inspections but I need to do something about this permanent DTC

If anyone has experience with this please let me know

Thanks

[RPMtech147]

You need to clear the fault with a proper scan tool (VCDS, Autologic, ODIS, etc). From my experience, a lot of the the little generic OBD code readers won't clear the "permanent faults" that seem to linger after you clear the stored and pending faults. That is odd that it failed. I would think as long as the monitors are ready and there's no pending/current faults, it should still pass, but Kali gonna Kali.

[Audisthesia]

The only way to clear a PDTC is to fix the underlying problem with the vehicle that originally caused the PDTC and its corresponding DTC to set, and then allow the vehicle sufficient drive time to re-run the monitor that identified the problem in the first place. When the monitor runs without identifying a problem, the PDTC will clear itself.

i.e. You can't clear it yourself. The car has to recognize the problem no longer exists and clear itself. You may want to look into why this has not occured.

[Audibellybutton]

Okay I get what you mean. Right now the only thing I can think of is going back and unplugging the thermostat plug again and plug it back in. The thermostat is brand new and functioning well with no leaks. It’s odd that it’s still there. I know it’s not unplugged either but maybe it needs some sort of electrical reminder that the problem is fixed

[RPMtech147]

The only way to clear a PDTC is to fix the underlying problem with the vehicle that originally caused the PDTC and its corresponding DTC to set, and then allow the vehicle sufficient drive time to re-run the monitor that identified the problem in the first place. When the monitor runs without identifying a problem, the PDTC will clear itself.

i.e. You can't clear it yourself. The car has to recognize the problem no longer exists and clear itself. You may want to look into why this has not occured.

This is incorrect. A proper tool will clear permanent codes. IE ODIS, STARTECH(MB), ISTA(BMW)

[Audibellybutton]

I cleared it with VCDS and it doesn’t show up on VCDS but for some reason it shows up on hotuners VCM scanner as a permanent DTC

Anyways here’s some pics for clarity

also the smog guy said some people say that it takes 20 cold start cycles and 200 miles of driving to clear it. Ive definitely done over 200 miles since the thermostat change but I dont think ive done 20 cold start cycles

[Audisthesia]

This is incorrect. A proper tool will clear permanent codes. IE ODIS, STARTECH(MB), ISTA(BMW)

In other words, dealer tools. Not something a consumer typically has at home. PDTC were intentionally designed to prevent the consumer from clearing them for legal and environmental reasons.

Earlier you said VCDS, which he stated did not do it.

You need to clear the fault with a proper scan tool (VCDS, Autologic, ODIS, etc). From my experience, a lot of the the little generic OBD code readers won't clear the "permanent faults" that seem to linger after you clear the stored and pending faults. That is odd that it failed. I would think as long as the monitors are ready and there's no pending/current faults, it should still pass, but Kali gonna Kali.

All stupid arguing aside, his car should have cleared the PDTC on it's own if the problem was repaired. So the real question is, why not?

[Audibellybutton]

In other words, dealer tools. Not something a consumer typically has at home. PDTC were intentionally designed to prevent the consumer from clearing them for legal and environmental reasons.

Earlier you said VCDS, which he stated did not do it.



All stupid arguing aside, his car should have cleared the PDTC on it's own if the problem was repaired. So the real question is, why not?

This whole permanent DTC thing is new to me but luckily I have found that on VCDS you can track your warm up cycles since your last DTC. On VCDS Home Screen click OBD11 and then choose read data. From the drop down menu you can choose the option "warm up cycles since DTC was last cleared"

I need to rack up 15-20 for the monitor to reset by itself. I did this repair a couple weeks ago and was not mindful of warm up cycles as I have cleared the DTC multiple times since the repair. Each time I clear DTC, even for an unrelated reason, it clears your warm up cycles as well. SO its very well possible that I did not hit 15-20 warm up cycles since last clearing DTC. So now that I am mindful of it I will complete the cycles and see if it goes away. It should, the thermostat is functioning properly. But anyways Ill report back about that

[Audisthesia]

This whole permanent DTC thing is new to me but luckily I have found that on VCDS you can track your warm up cycles since your last DTC. On VCDS Home Screen click OBD11 and then choose read data. From the drop down menu you can choose the option "warm up cycles since DTC was last cleared"

I need to rack up 15-20 for the monitor to reset by itself. I did this repair a couple weeks ago and was not mindful of warm up cycles as I have cleared the DTC multiple times since the repair. Each time I clear DTC, even for an unrelated reason, it clears your warm up cycles as well. SO its very well possible that I did not hit 15-20 warm up cycles since last clearing DTC. So now that I am mindful of it I will complete the cycles and see if it goes away. It should, the thermostat is functioning properly. But anyways Ill report back about that

Hopefully for you sake, it's just a matter of time before this goes away on it's own.

[Botbasher]

Even some of the low end OBD tools can clear the PDTCs... you just need to sequence them right.

Some DTCs fault multiple systems and clearing one won't clear another, which then allows the fault to return instantly. The other issue is what order you clear them in. Clearing in #2 module before clearing #1 will reset the fault in #2 via #1... a vicious cycle. This was in my 05 VW GLi with a ELM327 and Torque App where I learned this, so it's application my be limited here. Lots of things have changed since then.

I have not found a code that the OBD11 won't clear despite several being labeled "permanent" as long as the core fault is corrected. HPTuner (what I tune with) can also clear "permanent" codes without issue as well.

Cheers,

KS

[Audibellybutton]

Even some of the low end OBD tools can clear the PDTCs... you just need to sequence them right.

Some DTCs fault multiple systems and clearing one won't clear another, which then allows the fault to return instantly. The other issue is what order you clear them in. Clearing in #2 module before clearing #1 will reset the fault in #2 via #1... a vicious cycle. This was in my 05 VW GLi with a ELM327 and Torque App where I learned this, so it's application my be limited here. Lots of things have changed since then.

I have not found a code that the OBD11 won't clear despite several being labeled "permanent" as long as the core fault is corrected. HPTuner (what I tune with) can also clear "permanent" codes without issue as well.

Cheers,

KS

ive cleared the fault in hptuners as well but it still came back. Now im thinking maybe theres a short in the wiring? I'll have to visually inspect again but it looked fine. Either way Ill be doing the 15-20 warm up cycles because smog will pass it anyways if I complete that even if the permanent dec doesn't go away. I'm thinking it should with that and 200 miles of driving. Its really odd, but yeah I'll also check the wiring again with a multimeter when I have time to pull it back apart and get under there

[smwalker]

You cannot clear a permanent code with a scanner or battery disconnect. I suspect if people are doing it with HP tuners they are clearing and reinstalling the ECU file. That might do it but it's not necessary.

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
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.
See here: https://www.bar.ca.gov/Industry/PDTC

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. Not sure what those numbers are in an Audi. 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.

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.

https://www.youtube.com/watch?v=gswP3KlmfdI

[ericw.]

Yup what was said above by smwalker and Audisthesia.

You need drive cycles. Pay your reg fees for now and you at least won't have late fees. Get your smog done once you put miles/drive cycles on the car.