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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

Only bulletins with component: Equipment and accessories are shown. Show all

Bulletins, newest first
SM 05-20212021-02-04. Service bulletin. EQUIPMENT. This special notice is to inform dealers to return the parts listed if it meets the criteria provided.
A9121622061934_12021-02-04. Service bulletin. EQUIPMENT. This bulletin states to ignore DTCs U156C00, B1A06F1, B1A06F2 and to not perform any repairs or run any test plans for these ghost DTCs.
A4821922061904_12021-02-04. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; ELECTRICAL SYSTEM. This bulletin contains repair instruction for when DTC C110DF0 is stored and the yellow steering lamp is on.
A0121962060429_22021-02-04. Service bulletin. ENGINE AND ENGINE COOLING; EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY. This bulletin contains instructions for when there may be a noise from the exhaust flap or there are DTCs sporadically stored in the ECM.
A9120432061625_12021-01-08. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT:ELECTRICAL. SOS emergency call malfunction, DTC B129B11 and B129C11 are stored in the emergency call control module
A5320042043016_22021-01-08. Service bulletin. ELECTRICAL SYSTEM:PROPULSION SYSTEM: CABLES; EQUIPMENT. This bulletin contains repair instructions for when cables are hanging in view with no DTCs.
A5520512014055_82021-01-08. Service bulletin. EQUIPMENT; ENGINE; EQUIPMENT ADAPTIVE/MOBILITY. This bulletin contains instructions for addressing discoloration due to moisture on a new vehicle.
SM C-20202021-01-08. Service bulletin. EQUIPMENT. This special notice is to inform dealers to return the part numbers listed (State of California only).
A0020362002047_12020-12-21. Service bulletin. EQUIPMENT:ELECTRICAL. This information bulletin contains instructions for technicans on how to ensure their TAC call goes smoothly.
A9120362061345_12020-12-04. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. This informational bulletin contains information regarding connectivity issues.
A4620192061331_12020-12-04. Service bulletin. SERVICE BRAKES, AIR:ANTILOCK:ABS WARNING LIGHT; EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. This bulletin contains instructions for addressing an ABS warning light with DTCs C050200 and/or C050800.
A4620182061403_12020-12-04. Service bulletin. SERVICE BRAKES, AIR:DISC:PADS; EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. This bulletin contains instructions for addressing a brake pad wear indicator light with no DTCs.
2010-2021EngOil2020-12-04. Service bulletin. EQUIPMENT. Added Saga Part number for 0W40 oil: SAGA Part: G E55040S0
21A4S4TECHREP2020-11-05. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. Driver Assistance Section: ADDED: "Activate rear cross traffic assist (if equipped)"
A9120242026611_72020-11-05. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT. This bulletin contains a guide for troubleshooting HD radio issues.
A9120202061028_12020-11-05. Service bulletin. ELECTRICAL SYSTEM; EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY. This bulletin explains and troubleshoots when Audi connect does not have a green SOS light.
A9020732059891_32020-11-05. Service bulletin. EQUIPMENT; ELECTRICAL SYSTEM. This informational bulletin directs you to read the SSP and not perform any repairs for the concern.
A1720112060750_12020-11-05. Service bulletin. ENGINE AND ENGINE COOLING:ENGINE:OIL/LUBRICATION; EQUIPMENT. This bulletin contains instructions for using the UV additive to find engine oil leaks.
A0020422045316_52020-11-05. Service bulletin. EQUIPMENT ADAPTIVE/MOBILITY; ENGINE AND ENGINE COOLING:ENGINE. This bulletin contains information for diagnosing the Start/Stop system.
21AUUSMaint09202020-10-06. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. New Document
21AUTIRECHAINS2020-10-06. Service bulletin. TIRES; EQUIPMENT; WHEELS. Added new graphic to reflect where to find MY 21 information
A9120142060675_12020-10-06. Service bulletin. STRUCTURE; ELECTRICAL SYSTEM:ADAS:PARKING ASSIST:WARNING; ELECTRICAL SYSTEM:ADAS:PARKING ASSIST:SENSORS; EQUIPMENT:ELECTRICAL. This bulletin contains instructions for addressing the issue when the parking assist will intermittently alert the customer to an obstruction and the sensors look 'pushed in'.
A9120112037809_72020-10-06. Service bulletin. EQUIPMENT:ELECTRICAL:NAVIGATIONAL SYSTEM(GLOBAL POSITIONING SYSTEM). This informational bulletin contains instructions about updating the navigation map.
21A4S4TECHREP2020-10-06. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. Vehicle Preparation Section: ADDED: "FCC ID, and Model" to" Verify Audi phone box customer registration form is present in vehicle and add the serial number, FCC ID, and Model from Elsa (if equipped). See TSB 2051720" Media / Radio / SAT Section: ADDED: "Confirm SiriusXM is on and in an active state (can scroll through channels and hear music)" ADDED Phone Box Form to the end of the document
21A4S4ALRDCSDEL2020-10-06. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. Infotainment Section: ADDED: - Tune to SiriusXM and show SiriusXM presets and customize based on customers listening preferences - Show differences of SAT vs IP channels through the On Demand category in SiriusXM with 360L equipped vehicles

The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.