2018 Audi A4 Problems

A vehicle diagnostic scan dated 04/15/2026 showed electrical communication faults involving vehicle control modules. The scan showed U014100, described as “Lost Communication With Body Control Module ‘A’,” with status listed as passive/sporadic. The scan also showed U112100, described as “Data bus message missing,” with status listed as active/static. This is being reported as a safety concern because body-control module, gateway, and data-bus communication faults can affect vehicle electrical functions, warning systems, access/locking systems, lighting or body-control functions, driver information, and other vehicle systems that rely on module communication. The concern is especially important because the vehicle has had multiple intermittent electrical/body-control symptoms, including fuel-door/tank-flap electrical faults and other reported intermittent vehicle electrical concerns. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and the diagnostic scan report, electrical-system records, service communications, and related repair records are available if requested.

A vehicle diagnostic scan dated 04/15/2026 at approximately 88,502 miles showed a stored transmission electronics fault: P084100, described as “Transmission fluid pressure sensor/switch A range/performance,” with status listed as passive/sporadic. This indicates a transmission / powertrain control concern involving the transmission fluid pressure sensor, transmission electronics, wiring, control logic, pressure monitoring, or related powertrain components. The vehicle also has prior transmission/powertrain history, including a March 2023 transmission-pan-gasket concern documented in service records, so this later transmission electronics fault is being reported in that broader powertrain context. This is being reported as a safety concern because a transmission fluid pressure sensor or transmission-control fault can affect shifting, drivability, delayed engagement, slipping, harsh shifting, limp mode, reduced power, drivetrain damage, or loss of propulsion while driving. Even if the fault is intermittent, a transmission-control issue may create an unsafe condition if it occurs in traffic or during acceleration, merging, turning, or normal driving. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and the diagnostic scan report, transmission-related records, service records, manufacturer communications, and related communications are available if requested.

The rear-view camera intermittently fails to engage when the vehicle is shifted into reverse. When the camera does display, the image sometimes shows horizontal glitch lines/artifacts. This affects backing visibility and parking safety and creates a risk of collision with pedestrians, objects, vehicles, or property. The concern was reported to Audi service along with other electrical/driver-assistance symptoms, suggesting a possible camera, wiring, module, signal-processing, or broader electrical fault. No crash, fire, injury, or fatality occurred. This complaint is being submitted because the rear camera/reverse display is a backing-safety system and the intermittent failure is unpredictable. The vehicle/component is available for inspection, and photo/video evidence and service communications are available.

I am reporting recurring safety-related defects on my 2018 Audi A4 involving Automatic Emergency Braking, Forward Collision Warning, Audi pre sense/front-collision functionality, and related electrical/driver-assistance reliability. The AEB/forward-collision system has shown two unsafe intermittent behaviors. At times it has failed to activate as expected when crash-mitigation assistance appeared reasonably available. At other times it has unexpectedly warned, jolted, or applied braking when there was no apparent vehicle, object, pedestrian, or hazard close to the car. Unexpected braking or false intervention can startle the driver, create rear-end collision risk, and reduce confidence in the system. Failure to activate can also increase forward-collision risk. The system was not intentionally disabled by me, and I am not aware of any driver-caused obstruction, modification, or normal explanation. The condition is intermittent and may not appear during a brief service visit or basic fault-code scan. This concern was reported through Audi/dealer service channels, including a documented repair request identifying the AEB system as malfunctioning and failing to activate as designed. A later dealer communication stated that there were no stored AEB faults and later clarified that no work was done on the AEB system, no inspection or verification of AEB operation was performed, and confirmation of operation would require an additional estimate. I am reporting unresolved safety status because intermittent active-safety failures or false interventions may not store permanent DTCs, and lack of stored faults is not complete safety verification. I have not received final written safety closure confirming inspection, calibration review, road-test verification, factory scan/freeze-frame review, module communication review, and technical verification. No crash, fire, injury, or fatality is being reported. The vehicle is available for inspection if requested.

The short-term MPG / fuel-consumption display gives illogical and inconsistent readings. The display can show a significant drop in short-term fuel economy after the vehicle has been parked, locked, and not running, as if the system is incorrectly factoring parked/off time into the MPG calculation. This suggests a possible fault in the onboard computer, instrument cluster, fuel-consumption calculation, sensor input, software, ECU/module logic, or related electrical system. This is being reported as a safety concern because inaccurate fuel-consumption or range-related information can mislead the driver about fuel usage and remaining range, and it may indicate a broader vehicle electrical/computer/sensor malfunction. The concern is also part of a broader pattern of electrical or driver-information issues, including other intermittent warnings and display-related concerns. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and photos/video of the display, service communications, issue lists, and related electrical-system records are available if requested.

The engine oil level has been gradually dropping and has required monitoring and/or adding oil between normal service intervals. The exact source is unknown. It may involve abnormal oil consumption, an external oil leak, internal engine oil consumption, PCV/oil separator issue, turbo-related oil consumption, gasket/seal issue, or oil loss that is not leaving an obvious visible puddle. This is being reported as a safety concern because low engine oil or abnormal oil loss can lead to low oil pressure, warning messages, engine overheating or damage, smoke, oil contacting hot engine/exhaust components, limp mode, stalling, or loss of propulsion while driving. The issue should be inspected rather than treated as normal maintenance unless a proper diagnosis confirms normal operation. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and oil-level/refill records, repair records, photos, receipts, and service communications are available if requested.

A vehicle diagnostic scan dated 04/15/2026 showed electrical communication faults involving vehicle control modules. The scan showed U014100, described as “Lost Communication With Body Control Module ‘A’,” with status listed as passive/sporadic. The scan also showed U112100, described as “Data bus message missing,” with status listed as active/static. This is being reported as a safety concern because body-control module, gateway, and data-bus communication faults can affect vehicle electrical functions, warning systems, access/locking systems, lighting or body-control functions, driver information, and other vehicle systems that rely on module communication. The concern is especially important because the vehicle has had multiple intermittent electrical/body-control symptoms, including fuel-door/tank-flap electrical faults and other reported intermittent vehicle electrical concerns. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and the diagnostic scan report, electrical-system records, service communications, and related repair records are available if requested.

The vehicle has a recurring interior rattle / loose-trim concern involving interior panels, trim, speaker/subwoofer area, rear shelf, dashboard area, or related mounting components. The noise is not merely a comfort concern if it is caused by a loose component, fastener, grille, panel, or speaker housing that may move, worsen, detach, or distract the driver. This is being reported as a safety concern because loose interior trim or components can distract the driver, interfere with normal vehicle use, create uncertainty about whether a component is secured, and may indicate improper fastening, panel fitment, speaker/subwoofer mounting, or body/electrical component installation issues. If the affected trim is near safety-system areas, it should be inspected to confirm it does not affect wiring, restraint-system areas, visibility, or safe vehicle operation. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and service records, TSB-related records, photos/video/audio, issue lists, and repair communications are available if requested.

The engine oil level has been gradually dropping and has required monitoring and/or adding oil between normal service intervals. The exact source is unknown. It may involve abnormal oil consumption, an external oil leak, internal engine oil consumption, PCV/oil separator issue, turbo-related oil consumption, gasket/seal issue, or oil loss that is not leaving an obvious visible puddle. This is being reported as a safety concern because low engine oil or abnormal oil loss can lead to low oil pressure, warning messages, engine overheating or damage, smoke, oil contacting hot engine/exhaust components, limp mode, stalling, or loss of propulsion while driving. The issue should be inspected rather than treated as normal maintenance unless a proper diagnosis confirms normal operation. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and oil-level/refill records, repair records, photos, receipts, and service communications are available if requested.

The vehicle displayed a low coolant warning and the coolant reservoir was low. Audi dealer service records dated on or about 02/14/2025 document the concern as: “client states low coolant warning was on, coolant reservoir is low, diagnose and advise.” The dealer performed coolant-related work involving the thermostat gasket / coolant hoses or connections to the coolant reservoir, ran the vehicle to operating temperature, and rechecked. The concern is being reported because the coolant loss/refill issue continued or remained unresolved afterward. The exact source of coolant loss is unknown, but it may involve the water pump, thermostat, coolant reservoir, coolant hoses/pipes, pressure loss, internal coolant leak, or coolant loss that evaporates before leaving visible residue. This is a safety concern because coolant loss can lead to overheating, warning messages, limp mode, loss of propulsion, engine damage, steam/smoke, or stall risk while driving. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and Audi service records, coolant-system communications, photos, and water-pump/coolant-related documents are available.

A vehicle diagnostic scan dated 04/15/2026 at approximately 88,502 miles showed a stored transmission electronics fault: P084100, described as “Transmission fluid pressure sensor/switch A range/performance,” with status listed as passive/sporadic. This indicates a transmission / powertrain control concern involving the transmission fluid pressure sensor, transmission electronics, wiring, control logic, pressure monitoring, or related powertrain components. The vehicle also has prior transmission/powertrain history, including a March 2023 transmission-pan-gasket concern documented in service records, so this later transmission electronics fault is being reported in that broader powertrain context. This is being reported as a safety concern because a transmission fluid pressure sensor or transmission-control fault can affect shifting, drivability, delayed engagement, slipping, harsh shifting, limp mode, reduced power, drivetrain damage, or loss of propulsion while driving. Even if the fault is intermittent, a transmission-control issue may create an unsafe condition if it occurs in traffic or during acceleration, merging, turning, or normal driving. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and the diagnostic scan report, transmission-related records, service records, manufacturer communications, and related communications are available if requested.

See attached document for complaint

The vehicle is subject to a Passenger Occupant Detection System / PODS safety recall involving the front passenger seat occupant-detection system and passenger airbag status. The concern is that the system may incorrectly detect whether a passenger is seated and may switch off or affect the front passenger airbag when the seat is occupied. This is being reported because the recall remedy was not completed, was delayed, was not properly resolved, or the concern remains unresolved. A malfunctioning passenger occupant detection system can affect whether the passenger airbag deploys as intended in a crash. The issue involves the airbag system, front passenger seat occupant detection, related sensors/modules, and related electrical components. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and Audi recall documents, service records, communications, and any warning-light or passenger-airbag-status evidence are available if requested.

I first received notice of this recall in 1/22. My Audi dealer has continuously stated that Audi does not send them enough kits to remedy this recall

An Audi dealer installed 245/40R18 93H tires on this 2018 Audi A4, while the vehicle placard/specification requires 245/40R18 97H. The lower load index reduces capacity from 1,609 lb per tire to 1,433 lb per tire, approximately 704 lb total across four tires. This creates a safety risk because load-rated tires affect vehicle stability, heat buildup, braking, steering/cornering, suspension loading, and tire failure/blowout risk. After discovering the mismatch, the concern was reported to the dealer and Audi, but the dealer stated the 93H tires were acceptable rather than providing a safety-based correction. No crash, fire, injury, or fatality occurred. This complaint is being submitted because the vehicle may have been operated with under-rated tires and because the issue can affect handling, braking, tire durability, suspension/wheel components, and safe vehicle control. Tire/repair-order records, door-jamb placard evidence, load-index comparison evidence, and dealer communications are available.

Left front brake hose failed. Replaced both front hoses, bled and flushed the brake hoses as needed

An Audi dealer installed 245/40R18 93H tires on this 2018 Audi A4, while the vehicle placard/specification requires 245/40R18 97H. The lower load index reduces capacity from 1,609 lb per tire to 1,433 lb per tire, approximately 704 lb total across four tires. This creates a safety risk because load-rated tires affect vehicle stability, heat buildup, braking, steering/cornering, suspension loading, and tire failure/blowout risk. After discovering the mismatch, the concern was reported to the dealer and Audi, but the dealer stated the 93H tires were acceptable rather than providing a safety-based correction. No crash, fire, injury, or fatality occurred. This complaint is being submitted because the vehicle may have been operated with under-rated tires and because the issue can affect handling, braking, tire durability, suspension/wheel components, and safe vehicle control. Tire/repair-order records, door-jamb placard evidence, load-index comparison evidence, and dealer communications are available.

Fortunately no catastrophic failure or accident occurred. At about 40,000k miles the rear spring mounts are significantly corroded and need replacing. This appears to be a galvanic reaction that occurs due to a design flaw which shortens the life of the critical mounts. I’m told one could fail imminently and the other is headed that way. Had this failed in use the damage would be significant and caused an accident. The service advisor said that Audi is aware of the short lifespan and has an improved version that will be used in the repair. I have a video of one of the mounts and will request the parts when repaired.

An Audi dealer installed 245/40R18 93H tires on this 2018 Audi A4, while the vehicle placard/specification requires 245/40R18 97H. The lower load index reduces capacity from 1,609 lb per tire to 1,433 lb per tire, approximately 704 lb total across four tires. This creates a safety risk because load-rated tires affect vehicle stability, heat buildup, braking, steering/cornering, suspension loading, and tire failure/blowout risk. After discovering the mismatch, the concern was reported to the dealer and Audi, but the dealer stated the 93H tires were acceptable rather than providing a safety-based correction. No crash, fire, injury, or fatality occurred. This complaint is being submitted because the vehicle may have been operated with under-rated tires and because the issue can affect handling, braking, tire durability, suspension/wheel components, and safe vehicle control. Tire/repair-order records, door-jamb placard evidence, load-index comparison evidence, and dealer communications are available.

The vehicle is subject to a Passenger Occupant Detection System / PODS safety recall involving the front passenger seat occupant-detection system and passenger airbag status. The concern is that the system may incorrectly detect whether a passenger is seated and may switch off or affect the front passenger airbag when the seat is occupied. This is being reported because the recall remedy was not completed, was delayed, was not properly resolved, or the concern remains unresolved. A malfunctioning passenger occupant detection system can affect whether the passenger airbag deploys as intended in a crash. The issue involves the airbag system, front passenger seat occupant detection, related sensors/modules, and related electrical components. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and Audi recall documents, service records, communications, and any warning-light or passenger-airbag-status evidence are available if requested.

I was rear-ended at a slow speed. I was stopped at the time. The driver who hit me was decelerating hard. Damaged to rear bumper. When I got back in the car, I realized that telescoping steering column had been pulled toward me. This would have been bad had I been shoved into the car in front of me and the airbags deployed too close to me. Luckily, this did not happen.

The exterior side mirrors have intermittent electrical/memory malfunctions. When locking the vehicle, the side mirrors begin to fold, pause or glitch briefly, and then continue folding. Separately, when the vehicle is shifted into reverse, the right-side mirror tilts downward to assist with backing/parking, but when shifted back to drive or park, the mirror does not reliably return to its original saved position and requires manual readjustment. This is being reported as a safety concern because exterior mirror position affects rearward and side visibility, backing visibility, lane-change awareness, and the driver’s ability to maintain proper mirror alignment. An intermittent mirror control, folding, memory, or tilt malfunction may indicate an electrical, motor, control-module, wiring, switch, or mirror-memory issue. No crash, fire, injury, or fatality occurred. The vehicle/component is available for inspection, and service communications, issue lists, photos/video if available, and related electrical-system records are available.