Service bulletins for the 2020 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.
942 on file from NHTSA, as of 2026-10-19.
About U1421 on the 2020 Audi S4: what the code means, and the bulletins and recalls about the same components.
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Only bulletins with trouble code: U1421 are shown. Show all
| TSB_2056076_22 | 2025-04-04. Service bulletin. ELECTRICAL SYSTEM. This bulletin provides information when there is an SOS Malfunction with ConBox Low, "Emergency call function: fault", (DTC U142100, U153E00). |
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| A9124522056076_21 | 2024-10-28. Service bulletin. ELECTRICAL SYSTEM. This bulletin provides information when there is an SOS Malfunction with ConBox Low, "Emergency call function: fault", (DTC U142100, U153E00). |
| A9123492056076_2 | 2023-12-06. Service bulletin. UNKNOWN OR OTHER; COMMUNICATION:MANUFACTURER TELEMATICS. This bulletin provides information when there is no diagnostics communication to the telematics control module in vehicles with ConBox low; DTC U142100. |
| A9022732052299_5 | 2022-07-01. Service bulletin. EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL. This bulletin contains repair instructions for proper transport mode deactivation (DTC U142100, DTC P169A00, and U13EB00 ). |
| A9022462052299_4 | 2022-03-04. Service bulletin. EQUIPMENT. This bulletin contains repair instructions for proper transport mode deactivation (DTC U142100, DTC P169A00, and U13EB00 ). |
The summaries are NHTSA's. Each bulletin's page links NHTSA's copy of the manufacturer's document.