Audi Q7 check engine light comes on

Filed Oct 25, 2026 · Engine · NC

In XXX, my 2017 Audi Q7 3.0T unexpectedly lost engine power while traveling approximately 70 mph on a highway in [XXX]. A "Drive System Malfunction" warning appeared. The driver pulled over, shut off the engine, and restarted it; the vehicle then drove normally. The sudden reduction in power at highway speed created a risk of collision with surrounding traffic. The precise cause is UNKNOWN. I reported the highway-speed loss of power and warning to Audi Wilmington. At its XXX visit (102,255 miles), the dealership documented the warning and multiple engine misfire codes. It identified a vacuum leak at a broken oil-fill pipe neck, replaced the pipe, cleared codes, and reported no issue during its test drive. The intermittent power loss did not recur during that visit. The vehicle also had recurring excessive oil consumption. In XXX (104,261 miles), Audi Wilmington found it approximately 1.5 quarts low and documented possible piston-and-ring replacement if proposed treatments failed. Those proposed repairs were not performed. In XXX (approximately 109,320 miles), the vehicle again showed a Drive System Malfunction warning and check engine light. Maguire Audi documented multiple misfires and a persistent cylinder #2 misfire after service, and suspected internal engine damage. The vehicle has been out of service since then. Independent testing in XXX confirmed cylinder #2 had 35 PSI compression and 100% leak-down, with part of an exhaust valve missing and oil on the piston. The connection, if any, between the XXX power loss and later engine damage is UNKNOWN. Authorized Audi dealers and an independent shop have inspected the vehicle; I am unaware of any inspection by police, insurers, or the manufacturer. The vehicle remains in my possession and is available for inspection. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Sep 19, 2026 · Acceleration, Engine · CO

During summer 2026 the check-engine light on our 2019 Audi Q7 came on BEFORE its first August service/oil-change visit. The light remained on when the dealer returned the vehicle. Within days, the driver found cruise control no longer worked; it had worked before that visit. She called the dealer in mid-August to arrange a return. At the second visit, the dealer reported intake-manifold runner controls for banks 1 and 2 stuck closed and recorded: "water pump has failed internally, causing a vacuum leak". The water pump was replaced. After the second visit, around August 28, 2026, a high-pitched whining/squealing noise began. It occurred while coasting or going downhill and generally when the accelerator was not pressed, not only while braking. The driver initially suspected a brake noise. She recalls the dealer advising measures to remove excess brake material and saying it should not pose a safety risk. The noise persisted after those measures. At a third visit the dealer diagnosed a PCV/crankcase-breather issue. That repair remains outstanding. The earlier reassurance concerned a suspected brake noise before the PCV diagnosis. We request investigation of the persistent warning, cruise-control malfunction, diagnosed vacuum/intake-manifold issues and later PCV/noise complaint, including any safety implications for vehicle operation. Whether these faults are related is UNKNOWN; their timing alone does not establish that service caused them. Our specific concern is abnormal crankcase pressure from the PCV fault, including possible overpressure, oil leakage or seal damage and impaired engine operation in traffic. Actual pressure/vacuum measurements and any resulting damage are UNKNOWN; these are concerns for investigation, not confirmed events. Receipts are available. Actual fault codes, diagnostic tests, and repair records should be reviewed. Availability of removed parts for inspection is UNKNOWN.

Filed Sep 5, 2026 · Electrical · CA

The vehicle has a recurring electrical failure involving the camshaft position sensor circuit (DTC P0365). The sensor itself is functional, but the wiring harness leading to the sensor develops internal copper fatigue due to a design flaw in the factory routing. The harness is bent tightly behind the passenger-side cylinder head, causing vibration-induced internal wire breakage that is invisible externally. This failure is well known to Audi dealers and has been reproduced and confirmed by multiple service centers. The problem is not caused by the sensor, plug, or engine components. It is caused by the wiring harness design, which repeatedly fails in the same 6–10 inch section. The defect causes intermittent loss of camshaft signal, illumination of the check engine light, and inability to pass emissions. Repair requires cutting open the harness and splicing in new wire, costing approximately $700–$1,200 each time. This is a repeated electrical defect caused by poor harness routing and inadequate wire durability. This issue affects safety indirectly because the vehicle cannot reliably report camshaft position to the ECM, and the failure is unpredictable. The defect is widespread among vehicles using the same engine and harness design.

Filed Aug 7, 2026 · Acceleration, Electrical · GA

On startup, the instrument cluster (Audi Virtual Cockpit) takes an abnormally long time to illuminate. When it does come on, the check engine light and multiple other warning indicators are illuminated. First noticed about a month ago when the panel with the speed indicator wouldn't light up or took a long time to illuminate. I took the car to three dealerships before Audi mentioned that this is a manufacturing issue. The vehicle was taken to [XXX] Audi, Marietta, GA (Repair Order XXX) in XXX. The technician's diagnostic notes recorded a fault described as "control module for instrument cluster — optical data bus — no communication." The dealer referenced an internal Technical Service Bulletin describing an intermittent hardware defect in the Audi Virtual Cockpit logic module, attributed to a manufacturing/semiconductor issue at the supplier level. Per the TSB, if the instrument cluster's production date is before XXX, the cluster must be replaced. The dealer quoted $3,093.81 to replace the instrument cluster assembly. I am aware that the federal safety agency recall 25V201 (Audi internal number 90VC) covers 2021 Q7 vehicles for a related virtual cockpit shutdown defect, remedied with a free software update. INFORMATION REDACTED PURSUANT TO THE FREEDOM OF INFORMATION ACT (FOIA), 5 U.S.C. 552(B)(6)

Filed Jun 8, 2026 · Engine, Transmission · VA

I was traveling at highway speeds in active, high-velocity traffic when my vehicle suffered a sudden, catastrophic mechanical failure that nearly resulted in a severe multi-car accident. Without any warning, the vehicle completely lost its ability to accelerate, flatly refusing to pick up speed or maintain momentum despite pressing the gas pedal. ​This unexpected, immediate drop in propulsion marooned me in high-speed lanes, leaving the vehicle dangerously vulnerable as oncoming traffic rapidly closed the distance behind me. Drivers behind me were forced to aggressively swerve and brake to avoid a high-speed rear-end collision. Moments after this life-threatening loss of power occurred, the Check Engine Light illuminated on the dashboard. ​Subsequent technical inspection revealed a severe engineering defect: the internal seals of the factory coolant control components failed, forcing pressurized engine coolant backward into the engine’s primary vacuum system. This pressurized fluid completely contaminated the vacuum lines, the vacuum reservoir tank, and the electronic solenoids—including the N75 boost control solenoid. By filling the vacuum infrastructure with liquid coolant, the engine was instantly starved of its ability to regulate turbocharger boost, triggering a critical "limp mode" and a P0299 underboost fault. ​The catastrophic failure of an internal cooling seal directly compromising an active drivability safety system represents an unreasonable and severe defect. It transforms a routine drive into an immediate, uncontrollable highway hazard. I am filing this report because this known coolant migration pattern presents a clear, present, and life-threatening danger to owners operating this engine platform.

Filed May 20, 2026 · Engine · 60,000 miles · NC

The contact owns a 2021 Audi Q7. The contact stated that while driving approximately 50 - 55 MPH, the Check Engine light had illuminated. The vehicle was taken to the dealer, who diagnosed code PO299, which referred to coolant migration into the vacuum system. The contact was unable to provide the exact parts that were needed for repairs. The vehicle was not repaired. The manufacturer was informed of the failure. The manufacturer opened a case regarding the issue. The failure mileage was approximately 60,000.

Filed May 14, 2026 · Engine · WI

the first indication of an issue was oil consumption. It was using more oil than usual around the 70K mile mark. Then it started misfiring, and soon after a knocking noise coming from the engine. There are no check engine light on, after bringing it in for diagnostics, it read that it was a spark plug, once they got into the engine they discovered the cylinder had been stripped from the piston. Yes the diagnostics came from our foreign car mechanic. no, it has not been inspected by the manufacturer or police. Just the symptoms. sometimes the light would come on, and then it would go off. At this point it is off. All of this started in the fall of 2025.

Filed Mar 17, 2026 · NV

Start/Stop button will not start the engine at times. May take several attempts before engine will start. Had to have Audi Roadside Assist come to my location to get the vehicle car started. Drove vehicle to nearest dealer with the "engine light" illuminated. Was advised that Audi has a software update that needs to be installed. Update was supposed to drop by week 10 of 2026 but it is still not available as of week 12. Audi and the dealer cannot provide a resolution after vehicle has been in shop for 3 weeks. Was told that I could pick up the car since they did not see it as a safety issue, but if the vehicle if often unable to start why would one trust driving it?

Filed Mar 13, 2026 · Engine · 70,000 miles · FL

The contact owns a 2020 Audi Q7. The contact stated that while driving at an undisclosed speed, the transmission unexpectedly downshifted while the accelerator pedal was depressed. The check engine warning light was illuminated. The vehicle was taken to a local dealer, where the water pump, coolant pump, vacuum line, and vacuum reservoir were replaced. The manufacturer was made aware of the failure. The failure mileage was approximately 70,000.

Filed Feb 11, 2026 · Transmission · 120,000 miles · NC

The contact owns a 2017 Audi Q7. The contact stated that while driving approximately 65 MPH, the contact became aware of an abnormal odor. The vehicle started shaking, and the drive train malfunction indicator was displayed. The contact pulled over to the side of the road, and the vehicle was towed to an independent mechanic, where it was diagnosed and determined that the exhaust valve had burned a hole through cylinder #1 due to a misfire. The contact notified the dealer, but assistance was declined. The vehicle was not repaired. The manufacturer was notified of the failure. The failure mileage was 120,000.