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Service bulletins for the 2018 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.

796 on file from NHTSA, as of 2026-10-19.

By type

By component

By trouble code

By topic

Bulletins, newest first
SM 15-20212021-03-04. Service bulletin. EQUIPMENT. This special notice is to inform dealers to return the part numbers listed (State of California only).
AWA 21-012021-03-04. 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_12021-03-04. Service bulletin. ELECTRICAL SYSTEM. This bulletin contains guidance for submitting warranty wiring repairs.
A9421342012749_12021-03-04. Service bulletin. EXTERIOR LIGHTING. This bulletin contains instructions for addressing condensation in the headlights.
A4621222051095_42021-03-04. Service bulletin. EQUIPMENT. This informational bulletin contains instructions on how to download and use the Audi Frequency App.
A9421332061922_12021-03-04. Service bulletin. EQUIPMENT. This informational contains instruction on how to document optical concerns for warranty claims.
A4621242034181182021-03-04. Service bulletin. SERVICE BRAKES. This technical service bulletin provides troubleshooting for brake noise.
A4621232022584102021-03-04. Service bulletin. SERVICE BRAKES. This informational bulletin provides diagnostic information for brake conditions.
A4421802056386_42021-03-04. Service bulletin. STEERING. This bulletin contains instructions for when the vehicle pulls to one side or the steering wheel is crooked.
A6621692030471_62021-03-04. Service bulletin. EQUIPMENT. This informational bulletin covers the condition of when license plate mounting bracket threaded inserts are stripped.
A4421792022563_12021-03-04. Service bulletin. WHEELS. This bulletin provides information regarding vibrations or movement that are felt in the wheel.
A1721122060750_22021-03-04. Service bulletin. ENGINE AND ENGINE COOLING. This bulletin contains instructions for using the UV additive to find engine oil leaks.
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.
A9121642024323_72021-02-04. Service bulletin. PARKING BRAKE:ELECTRICAL:CONTROL MODULE. This bulletin contains technical information regarding when the parking aid sporadically warns of obstacles that don't exist or it is inoperative/constant warning.
A1921112061918_12021-02-04. Service bulletin. ENGINE AND ENGINE COOLING. This bulletin provides guidance on diagnosing a coolant light concern with normal coolant level in the tank.
A6621682046229_22021-02-04. Service bulletin. STRUCTURE. This informational bulletin outlines proper warranty procedure for optical defects.
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.
A9120412060681_22021-01-08. Service bulletin. ELECTRICAL SYSTEM:SOFTWARE; EQUIPMENT ADAPTIVE/MOBILITY; EQUIPMENT. This bulletin contains instructions to update eligible cars from Google Earth to the new service provided by HERE.
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.
A3920382060169_22021-01-08. Service bulletin. ELECTRICAL SYSTEM. This bulletin contains instructions for when DTC U101300 is logged with sports differential warning lamps or messages.
A3920392051558_52021-01-08. Service bulletin. EQUIPMENT; EQUIPMENT ADAPTIVE/MOBILITY; ELECTRICAL SYSTEM: INSTRUMENT CLUSTER/PANEL. This bulletin contains repair instructions for when the message "four-wheel drive malfunction" shows up sporadically in the instrument cluster with DTC C05ED00.
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.

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