Stability Control Malfunction Light

[RobPenn05]

2014 Q5 2.0L with 131K miles recently started to show intermittent Stability Control Failure followed by TPMS light. Stays on for a short period ( typically < 2 minutes) then goes off. Understand TPMS is part of the ESC. Multiple codes are set when scanned (I didn’t scan, shop did). Check engine light eventually comes on.

Independent shop did smoke test and found leaks in the upper timing chain gasket and losing pressure so was replaced. Had been telling me for a while this was going to need to be done at some point. Did not correct.
Tried replacing the MAF sensor along with retesting for leaks after replacing, checking for loose/broken wires and such with no success. Put old MAF sensor back and didn’t charge for that since didn’t resolve. Suggested taking it to dealer.

Dealer is saying replace the PVC valve first as that is the cause of the check engine light and might then be causing the ESC warning. Said it was "lean fuel". Would not do anything else until this was done (wanting nearly $1000 including the $220 “diagnostic” fee to tell me my brakes, tires and such were all good but my washer fluid level was low).

Independent shop is suspect if the PVC would address the issue as he didn’t see that as a concern, but will replace for much less than the dealer. Understand they can fail, especially in an older, higher mileage vehicle. Car seems to be running fine, not hesitant and such.

Looking for thoughts on if the PVC replacement would address the issue or other items to look for. Independent also suggested it could be a software issue, but dealer dismissed that due to the PVC issue they saw.

Replacing the PVC looks fairly straightforward, but I’m not typically one who would do this type of work myself although I have done brakes and such on other vehicles in the past.

Somewhat hesitant at this point to just start throwing parts at it which is what I’m starting to feel like is happening.

Thanks!

[djn876]

Step one, find a new shop, step two, find a new dealer.

The PCV may need to be done, but has nothing to do with the TPMS or the stability control if those are the codes you are getting. And they probably just want to play parts darts and get you to spend some money for crap that won't address your problem. Who knows maybe I'm way off, but the 3.0T has a ton of PCV issues out there and zero of them cause what you are describing. PCV is usually a rougher idle, coolant loss, excessive oil consumption, excessive crankcase vacuum.

Also, a timing chain cover leak causing a TPMS or stability control problem? Other than oil leak, it won't do any of those things. That's just silly.

Can you post the actual codes here?

Do you have any issues or codes with the ABS? My first thought would be something like a wheel speed sensor. The TPMS has nothing to do with stability control, other than Audi uses the wheel speed sensors to determine if a tire is underinflated by comparing the rotational speed of each wheel, it does not use this information for anything else, just that the sensor is shared.

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[MSq5]

Step one, find a new shop, step two, find a new dealer.

The PCV may need to be done, but has nothing to do with the TPMS or the stability control if those are the codes you are getting. And they probably just want to play parts darts and get you to spend some money for crap that won't address your problem. Who knows maybe I'm way off, but the 3.0T has a ton of PCV issues out there and zero of them cause what you are describing. PCV is usually a rougher idle, coolant loss, excessive oil consumption, excessive crankcase vacuum.

Also, a timing chain cover leak causing a TPMS or stability control problem? Other than oil leak, it won't do any of those things. That's just silly.

Can you post the actual codes here?

Do you have any issues or codes with the ABS? My first thought would be something like a wheel speed sensor. The TPMS has nothing to do with stability control, other than Audi uses the wheel speed sensors to determine if a tire is underinflated by comparing the rotational speed of each wheel, it does not use this information for anything else, just that the sensor is shared.

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This is spot on advice.

Another thought - simply a low tire. A low tire will trigger TPMS and maybe stability control as that tire will not rotate at the same tire speed as the others. Use a manual tire pressure gauge. Set them properly. Then go in MMI and reset tire pressures as correct. You may have to drive a few miles, a few key on, key off cycles to reset the TPMS sensor and monitor.

On many cars, if tire pressure is right on the threshold of triggering the sensor you can trigger a light and code that will be intermittent. Worth checking. Costs nothing.

If that doesn't work, you probably have a bad tire pressure sensor. Any tire store can replace it for maybe $25.

And get an actual code scan and report the code numbers here.

[pdnation]

This is spot on advice.

Another thought - simply a low tire. A low tire will trigger TPMS and maybe stability control as that tire will not rotate at the same tire speed as the others. Use a manual tire pressure gauge. Set them properly. Then go in MMI and reset tire pressures as correct. You may have to drive a few miles, a few key on, key off cycles to reset the TPMS sensor and monitor.

On many cars, if tire pressure is right on the threshold of triggering the sensor you can trigger a light and code that will be intermittent. Worth checking. Costs nothing.

If that doesn't work, you probably have a bad tire pressure sensor. Any tire store can replace it for maybe $25.

And get an actual code scan and report the code numbers here.

Everything you said is mostly correct. These cars have a passive TPMS. There is no tire pressure sensor. The system simply monitors the wheel speed sensors and detects when one or more disagree. Then it is assumed that you have a low tire pressure.


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[MSq5]

Everything you said is mostly correct. These cars have a passive TPMS. There is no tire pressure sensor. The system simply monitors the wheel speed sensors and detects when one or more disagree. Then it is assumed that you have a low tire pressure.


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Good to know about ABS and passive TPMS. OP probably does have a wheel speed difference. Hopefully, its just a low tire.

[RobPenn05]

Thanks for the suggestions! Tire pressure was correct in all 4, so I did a reset on the TPMS. I went ahead and replaced the PCV valve as suggested by the dealer (did myself) and cleared all the codes. Valve seemed a bit sticky compared to the new one, but certainly was not stuck. So far so good, no CEL and no Stability Control or TPMs indicators. Have driven about 100 miles so far over several trips of varying distance. By far the longest without the indicators coming on.