I have a 2013 Q7 S-line Prestige. It has nearly 150k miles on it. I have this issue come up twice, about 6 months apart. While driving on the freeway the ESC and TPMS lights come on, and the car then has a vibration. Even at low speeds, you can hear/feel it when pressing the accelerator. In both cases, pulling over and completely shutting the car down and then restarting fully fixes the issue. The lights go away, and the car drives normally. Seems like this must be some kind of a sensor fault or related, such that a "reboot" fixes it. Any thoughts as to what specifically could be causing this and whether it can be repaired without taking it to a shop?

 

Hi there!

The Q7 appears on the surface to be quite analog, but in reality it is full of electronics, including a fly-by-wire throttle pedal.

Your issue, I'm sure, can be associated with myriad archival threads on here and elsewhere, but just remember that in the case of 'sensor faults' the underlying cause may be something you wouldn't think of. On mine, when I'd cross RR tracks or uneven surfaces like that, my traction control would activate and vibrate (cycling the ABS system), throwing up the dash lights temporarily, and reducing power, or dropping the car out of cruise control related to the ESC system triggered. Owners often forget about the height sensors on the Q7, but they are easy to service (remove the bits, clean, lubricate, replace on car...or as minimum lubricate while installed on the car, etc.), and my issue was crusty height sensors.

When it comes to the electronics stuff, you've really got to scan the car for fault codes using a VAGCOM compatible scan tool....VAG = Volkswagen Auto Group, etc. A basic VAGCOM scan tool is cheap. If you want one that actually helps you to DIY diagnose and fix this car, then the Ross-Tech VCDS cost you about 1 hour of labor time at the Audi dealer, or what they charge you to scan the car one time...for some perspective.

Here's a thread were multiple owners chime in with their experience of the exact same TPMS/ESC lights/vibration and/or power reduction issue, and the scenario outcomes/root-cause differ widely between owners, so read all the way through to end:

https://www.audiworld.com/forums/q7-...2906407/page2/

 

First, I agree with '10Q7
Next, how much oil does it use?
I had the exact same thing happen one fateful night last sept. and I limped off the highway, shut it down, looked for anything out of order (found nothing), but mine did not "reboot", and I limped 15 miles home after dark with only fog lights showing me the way.
Mine was using more oil than I care to share (1quart/700ish miles)
It was a misfire on #5 and has been down ever since. And I believe the shop broke the valve, just mentioning.
I have it in a different shop for replacing the valve causing no compression, being completely rebuilt.

 

Thank you both for the replies! I may have an idea of the issue from the readings and current testing.

When this first happened late last year, I put a scanner on it, but I did not see any relevant codes. When this just happened again, I stupidly didn't bother with the scanner, thinking I would get the same. However, that is not the case. BlueDriver has shown me codes P0304 and P0303 indicating a misfire on cylinders 4&3. Additionally, it shows P130A and U1017. I understand that a misfire could cause the issue I experienced. I went to the Mode 6 option of the app to see live data. That has shown me a single misfire in the last 10 drives, on cylinders 3, 5 & 6. Oddly, it shows nothing happened on cylinder 4 as the scan code showed. I wish I could get date/time of the misfire, which would conclusively tell me if that occurred when my issues showed up, so this is an assumption of mine.

I actually changed my sparkplugs in January of this year. So after the first occurrence and some 4 months before this one. I replaced with OEM NGK. I am not seeing any live misfires and the count as mentioned is only 1 over the last 10 drives. That said, and I guess I'd expect zero misfires, so is this something that I should look to tackle or is a single misfire something I should let go?

I was asked about oil consumption. Not surprisingly, the car does consume oil as Audi's are wont to do. I tend to get the light that it's low after a few thousand miles. So not nearly as terrible as others getting it under 1k miles.

Thanks for any additional direction here!

 

The 3.0T engines are known for PCV failure issues (TSB issued), and also for increasing oil consumption due to carbon-captured piston rings. This topic is discussed ad-nauseum in other and dedicated threads, so won't get into that further.

Those Bluetooth dongle-type scan tools are convenient, but don't provide the details you get with the VCDS Ross-Tech VAGCOM or some other better VAGCOM tools. I keep my OBD-eleven in the glove box for basic health scan use only, as it's convenient and tiny. For diagnostics I pull out the VCDS.

If you DIY'd the plugs and are now seeing fault codes popping for misfires again, then it's pretty much either down to plug gap and/or the coils going out creating multiple misfires, if all the coil pack electrical connects are locked in tight, etc. Also consider what the old plugs condition was; any oil-fouling seen on plugs from those same cylinders? If you didn't verify the gaps on new plugs correct prior to installing...ask me how I know; just had that happen on my son's truck, but upon inspection it was clear that plug or box it was in had been dropped...shocking that it ran clean initially at all.

So, it's dealer's choice on how to proceed, but given that you very recently changed the plugs out and are seeing multiple misfires reported, I'd be pulling the plugs to verify condition and correct any electrode gap problems on them, as well as check for 'carbon tracking' from misfires on the inside of those plug boots (coil pack boots) and where the boot sits on the plug body, etc. Just remember the coil packs are programmed to the cylinder they reside on in the ECU, so you need to keep track of them. Once all the plugs gap/condition (also look for cracks on external insulator, etc) checks out 100%, you can swap plugs between the cylinders that weren't misfiring and those that were (test #1). If you found there were some issues with the plugs gap or other issues, then this allows confirmation the plugs are all good now. If they aren't the misfire will follow the plugs you moved. So, if the misfire stays with same cylinders, then you know it's a coil problem.

You could also start by swapping coils to see if the misfire moves with coil, but like I said those are programmed to ECU and you introduced a new variable with having swapped the plugs recently and now seeing misfires occur on diff cylinders, etc., so that's why I'd suggest start with the plugs, while definitely paying attention to those signs of carbon-tracking/misfire inside the coil boots on impacted cylinders. Not sure if you used any di-electric grease on those coil boots during plug swap, but that is helpful to prevent misfires and also to make it much easier to remove the coils at some future date.

FWIW:
My son put in the plugs, and I told him he should verify the plug gap correct, even though the plug boxes were the OE plugs that say factory gapped and can't be changed, etc. (iridium plugs) Next day he tells me it is idling rough/misfiring and asked me to look it over.
Scanned it; had error code of misfire, so swapped the coil over to diff cylinder and rechecked it. Misfire stayed on same cylinder, which meant the plug was the issue. Pulled plug, and wow, was that ground electrode just almost touching the plug core wire...crazy bad gap...not even close; the plug box had clearly been dropped, so checked plug for any cracks/damage otherwise...found none, so re-gapped the plug very carefully and used feeler gauge to ensure correct gap, which I also compared to a different new plug, and the old, worn plugs that came out just as reference point. Put back together and it fired up quick and running cleanly. My point being, it's easy to overlook the basics of a 'tune-up' in this world of pre-gapped spark plugs, but assuming they are correct & all the same gap can get you into trouble. And that's how I know...I got to troubleshoot and fix the misfire issue my son created by not checking the new plug gaps prior to installing them.

 

Thanks for the reply! The plug change was 4 months ago, and it looks like we are talking only one misfire. That said, I did check the gaps and in fact sent the initial plugs I bought back, as they were not at all in spec. The second set met the expected gap requirements. Since these are not regularly misfiring, I am not sure I will be able to tell anything by swapping. So far, the main issue has occurred twice, 6 months apart. I can only assume that not experiencing an active issue makes this much more complicated.

 

This is what my 15 does whenever it experiences a misfire. Mine has only been regulated to Cylinder 6 though, still trying to figure out the cause because I had all new plugs put in and gapped correctly about a month ago. 2 weeks after, had a misfire again. I think my issue is fuel related though, just have to track it down.

 

Agreeing again with '10Q7, PCV may be bad. I had mine changed because of coolant leak, I went from 1 quart between 10K service, to 700 miles. You may need that changed.
However, I would HIGHLY recommend, learning from my mistakes, to do a piston soak and an oil flush at next change. This will clean the rings and passages completely, restoring power! This brought my compression from 90s back to 150 in the couple cylinders documented. All were 150 excepting #5 with a bad valve (now being repaired)
That is a great start.That could very well fix your usage issue. I believe it could cure your misfires. Get out ahead of it, had I known? I would have done more than this and still been driving it today.
Good luck.

 

There's can be multiple reasons you get a random misfire, like the OP is getting now.

As you checked the plugs gap before installing and there was no sign of oil fouling or oil on the threads of the old plugs removed, I'd say the plugs are not your worry.

If oil was present on any of the old plugs...that's generally due to needs new valve-cover gasket, and/or may or not need a valve cover, as the plastic covers often will warp & then leak, etc. Just covering all bases here.

If there's no 'active' misfire, then I'd be chasing down/attacking the oil consumption problem, which can impact misfires, as well as eventually kill your engine. There are basic signs/symptoms of a failed PCV you can check for. If you are losing a liter of oil every few thousand miles, I'd call that excessive, even though you're at 150k miles, because we know the low-tension rings used on the 3.0T engine are frequently subject to carbon-capture, which leads to increasing oil consumption over time.

The defining tell of PCV oil consumption is that it manifests all at once/rapidly, versus the piston rings capture takes a long time to ramp up the oil consumption level, but it will get steadily worse if nothing else changes. When experienced together, the oil use is generally quite extreme. PCV on 3.0T engine is an extremely common failure point; dedicated threads on that and TSBs exist from Audi. There are other bits to do while the supercharger is removed under there as well as on the S/C too, so read all about it first, and don't leap to replacing the PCV unless there are definite failure symptoms from the PCV or thermostat, etc., etc.

The low-tension piston rings Audi doesn't talk about or suggest a fix; they just tell you oil consumption up to a Qt / 1000 miles is 'acceptable' usage. C'mon...it's really not 'acceptable' for this engine...increasing oil consumption is a cry for help. The prevention is 5k mile oil changes; the fix is get the rings freed up again using chemical products. If you want to check/verify...do a compression and leak-down test on your car's cylinders.

Then there's the carbon build-up on the intake valves that occurs simply due to being a DI-only type engine, and not even mentioning the PCV issues, and that carbon on valves can mess with your air/fuel mix stoichiometry, etc. At 150k miles on original injectors, those could also be involved, and injector balance and flow rates can be monitored live via VCDS and similar scan tools.

Definitely check those silly plastic height sensors and clean/lube them up; I know this sounds insanely unrelated to the oil consumption, and it is. It does, however, relate to the other issues with the lights coming on and traction control system, jerky headlights leveling, and in that case the power loss relates to what the car believes is happening due to the sensor feedback loops it is monitoring. Nobody thinks about the height sensors and how integrated they are on this car. That's a super cheap fix if you can just clean & lube those old suckers. Videos online show how to remove them, clean, and grease up the moving parts to restore normal functionality...simple DIY.


I'd be laser focused on reducing the oil consumption, and servicing those crusty, old, height sensors.

Best!

 

Correct and this i what I am currently dealing with, all of it!
Like said, get out in front of it before your engine looks like mine, in a 1000 pieces!