B1E21 on Ram vehicles

A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.

Bulletins and campaigns Ram filed with NHTSA whose summary names B1E21. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

• 08-394-25 Service bulletin
  2025-12-05 · Electrical System
• Telematics Box Module (TBM) Backup Battery Replacement When DTC B1E21 Is Present echnicians may experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may exhibit/set the following Diagnostic Trouble Code (DTC): ● B1E21-96 - Backup Battery Component Internal Failure
• 08-394-25 REV. A Service bulletin
  2025-12-12 · Electrical System
• Telematics Box Module (TBM) Backup Battery Replacement When DTC B1E21 Is Present Technicians may experience a Malfunction Indicator Lamp (MIL) illumination and the vehicle may exhibit/set the following Diagnostic Trouble Code (DTC): ● B1E21-96 - Backup Battery Component Internal Failure.
• 9100786 Service bulletin
  2026-03-30 · Electrical System
• TBM2.0H Setting U0080-00. Do not replace TBM ECU or SGW. Under certain conditions, SGW Module may take longer to establish Ethernet communication after boot up. If it takes longer than 30 seconds, The TBM2.0H module will set DTC U0080 - Ethernet Bus 1. As soon as SGW responds, the TBM2.0H will demature the DTC and move it to STORED. This issue should not cause any customer related symptoms. Do not

A stored code names the test that failed, never the part that caused it. The record above is what Ram and its owners have filed about it; the code’s page across every make has the whole file.