Service bulletins for the 2021 Audi S4
A bulletin is a manufacturer's communication to its dealers, as NHTSA indexes it. The summary is NHTSA's. The document is the manufacturer's: read it at NHTSA. A bulletin is not a recall, and listing a model year does not mean every vehicle of it is concerned.
969 on file from NHTSA, as of 2026-10-19.
By type
By component
By trouble code
| A9021002032113_5 | 2021-05-06. Service bulletin. EQUIPMENT. This information bulletin contains a background on the outside air temperature reading. |
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| A9021992063038_1 | 2021-05-06. Service bulletin. ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL; ELECTRICAL SYSTEM. This informational bulletin explains why the version information pops-up. |
| A6421792047061_3 | 2021-05-06. Service bulletin. EQUIPMENT:OTHER:LABELS. This bulletin contains a cleaning procedure from leftover residue from suction cups or labels. |
| A9121882062115_4 | 2021-05-06. Service bulletin. EQUIPMENT; EQUIPMENT:ELECTRICAL:NAVIGATIONAL SYSTEM(GLOBAL POSITIONING SYSTEM). This bulletin contains instructions for when the nav files are corrupted during an update. |
| A5721752022032_9 | 2021-05-06. Service bulletin. LATCHES/LOCKS/LINKAGES; ELECTRICAL SYSTEM. This technical service bulletin provides troubleshooting information for the vehicle locking system. |
| A5521542062730_1 | 2021-05-06. Service bulletin. EQUIPMENT. This bulletin explains why the compartment lid cannot be closed using the buttons on the key sometimes. |
| A9121862062713_1 | 2021-04-06. Service bulletin. EQUIPMENT. This bulletin contains repair instructions for when there is radio static when the rear heater is active. |
| A5521532062669_1 | 2021-04-06. Service bulletin. ENGINE AND ENGINE COOLING. This bulletin states that this is a normal condition and to not perform any repairs. |
| A0121012054893_5 | 2021-04-06. Service bulletin. ENGINE AND ENGINE COOLING. This bulletin contains instructions for documenting the "Please reduce Oil Level" message in the instrument cluster potentially with an Engine Warmup request. |
| A9421362023322_3 | 2021-04-06. Service bulletin. EXTERIOR LIGHTING. This informational bulletin contains information on the different shading of LED headlights. |
| A8021112062583_1 | 2021-04-06. Service bulletin. EQUIPMENT. This bulletin contains instructions for addressing an insufficient or uneven heating performance from the HVAC system. |
| A9121822062115_3 | 2021-04-06. Service bulletin. ELECTRICAL SYSTEM. This bulletin contains instructions for when the nav files are corrupted during an update. |
| A4821962055733_2 | 2021-04-06. Service bulletin. STEERING. This bulletin contains repair instructions for repositioning the intermediate steering shaft when there is squeaking noises from the steering column. |
| A1321132062387_1 | 2021-04-06. Service bulletin. ENGINE AND ENGINE COOLING. This bulletin contains instructions for determining if a repair is needed when coolant touches a poly V-belt and/or a toothed belt. |
| SM 17-2021 | 2021-04-06. Service bulletin. ELECTRICAL SYSTEM. This special notice is to inform dealers to return the parts listed if it meets the criteria provided. |
| A9121762037809_8 | 2021-04-06. Service bulletin. EQUIPMENT. This informational bulletin contains instructions about updating the navigation map. |
| A1921122061918_2 | 2021-04-06. Service bulletin. ENGINE AND ENGINE COOLING. This bulletin provides guidance on diagnosing a coolant light concern with normal coolant level in the tank. |
| A0121992054893_4 | 2021-04-06. Service bulletin. ELECTRICAL SYSTEM. This bulletin contains instructions for documenting the "Please reduce Oil Level" message in the instrument cluster potentially with an Engine Warmup request. |
| A5721742058452_2 | 2021-03-04. Service bulletin. VISIBILITY. This bulletin contains repair instructions for when the rear window defog button will light up and then turn off. |
| 21TechRefGde221 | 2021-03-04. Service bulletin. EQUIPMENT. Q5: Vehicle Prepartion Section: REMOVED: "Set adaption channel to enable CD Ripping using Guided Functions" Settings Section: REMOVED: "(if equipped)" from Turn off Manual Speed Warning On Hoist Inspection Section: ADDED to Install Wheel Bolt Covers: "When installing, ensure proper alignment to the valve stem (indentation in the wheel) lines up with the tab on the center cap to ensure correct mounting" Driver Assistance Section: REMOVED "(if equipped)" from "Verify operation of parking system" |
| A4721082055646_2 | 2021-03-04. Service bulletin. SERVICE BRAKES. This bulletin contains repair instructions for when the vehicle sporadically does not start and there is a hard brake pedal concern. |
| A4621252054385_2 | 2021-03-04. Service bulletin. EQUIPMENT; SERVICE BRAKES. This informational contains an explanation for when the customer hears creaking noises when braking at almost standstill (crawling when pulling away or briefly before standstill). |
| SM 15-2021 | 2021-03-04. Service bulletin. EQUIPMENT. This special notice is to inform dealers to return the part numbers listed (State of California only). |
| AWA 21-01 | 2021-03-04. Service bulletin. EQUIPMENT:APPLIANCE:AIR CONDITIONER. This Document informs dealers on the new A/C evaporator warranty extension for 2017-2021 A4/S4/Q7 and 2018-2021 A5/S5/Q5 vehicles |
| A9721782061976_1 | 2021-03-04. Service bulletin. ELECTRICAL SYSTEM. This bulletin contains guidance for submitting warranty wiring repairs. |
The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.