Audi has some pretty reliable vehicles in their production lines, but not all of them rank high in reliability ratings as we’d like them to be. Problems plague some of them, and owners won’t recommend them to other buyers. One such headache is the Audi Q7, a luxury SUV model.

It offers many impressive amenities and has that classic luxurious look, but those who’ve owned one over the years have many tales of woes to tell. RepairPal shows some of the most common problems the Q7 brings.

The Audi Q7 has engine misfiring problems

Audi Q7 owners reported that when they start the engine cold, the vehicle will buck and shudder while driving. Idling wavers up and down and usually, the check engine light comes on. Diagnostic scanners will show that there’s a random cylinder misfiring problem, or it will show specific cylinders having troubles firing up. Some drivers could simply wait for the vehicle to warm up long enough for the RPMs to even out and quit bouncing up and down. Not all owners found this to be the case, though.

Local dealerships evaluated the issue, and some reported that there wasn’t a problem. When the owners continued to complain, they checked into it further and then reported that it was because of poor fuel or carbon build-up in the cylinders. They could clean out those valves thoroughly, but it would cost the consumer around $1,390 to get it done.

They had spark plugs, coils, and wires replaced also, but that didn’t have any effect on the misfiring problems. One owner with a 2009 model said he had a crankshaft timing problem that cost $8,000 to fix. One repair to consider, for some models, is to have the Power Control Module software updated, which will fix the problem for a handful of owners.

A knock sensor problem

Often, Audi Q7 owners will drive down the road and find their check engine light is on and in the solid illumination state. No performance issues noted, but sometimes the knock (NOX) sensor light will show up on the dash. It will stay on for a while and then shut off only to come back on randomly later. There’s no difference in the way the vehicle drives, though.

When taking it to the dealer, the technicians report that there’s a problem with the knock sensor and it will need replacing. The cost, however, will run the owners around $500. While that fixes the problem, the issue will usually return later on after 1,000-20,000 miles. The Repair Pal technicians report that a better-designed knock sensor with an appropriate bracket should be installed. Also, you should surround it with some type of heat shielding material to protect it and that should take care of the problem.

The Audi Q7’s fuel tank pressurization issue

Owners reported that they started hearing a popping noise that sounded like it came from the trunk area. They also state that sometimes they would have a no-start situation right after fueling up at a gas station. The check engine light would come on, resulting in trouble diagnostic codes of P2404 and P0441. These indicate a pressurization problem, which is why there’s a popping noise. It’s from air filling the fuel tank and then being released to test the system.

The problem is from a faulty valve, located on the top of the intake manifold known as the Evap purge or N80 valve. Under normal conditions, the valve would close for pressure build-up in the fuel tank. When the valve wears out or breaks down, it will no longer close all the way. Part of it remains open, thus preventing any pressure from being able to build up in the tank. Replacing this valve with a newer version will fix the problem so the car can start again as needed.

The Audi Q7 hasn’t had the best history when it comes to reliability. The 2019 version of this luxury SUV, however, has seen better reliability ratings from Consumer Reports. If this type of sports utility vehicle is something you’re interested in buying, choose either the 2019 model or go for a used model from another automaker.