B1E21
0 owner reports and 289 manufacturer filings across 99 model years from Alfa Romeo, Chrysler, Dodge, Jeep and others.
Where B1E21 shows up
Source: NHTSA manufacturer communications and complaintsShowing the 25 model years where B1E21 appears most; it is on file for 99 in total.
A model year appears here because the code is named in its record, not because every one of these vehicles sets it. Counts are mentions in the federal files, not failure rates — nobody publishes the denominator.
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B1E21 by make
The same record, one make at a time: the model years, bulletins and owner reports that name B1E21 on that maker’s vehicles.
What it gets filed under
289 manufacturer filings name B1E21. Start with what the maker wrote down.
A code names the test that failed, not the part. A bulletin that names it is often a diagnosis someone has already written down — quote its number at the service desk.
Manufacturer filings that name it
Source: NHTSA manufacturer communicationsService bulletins and campaigns whose filed summary names B1E21.
- 9100786 Rev 1 Service bulletin2026-05-14 · Electrical System
- TBM2.0H Setting U0080-00. Do not replace TBM ECU or SGW. If replacement is determined, Verify "Z" part number availability. Order a "Z" part number for all Exchange Orders, Warranty, Mopar, Customer Pay and Service Contract. Order "68" part number for New, Unsold units only. Under certain conditions, SGW Module may take longer to establish Ethernet communication after boot up. If it takes longer t
- 9100786 Service bulletin2026-03-30 · 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
- 08-394-25 REV. A Service bulletin2025-12-12 · 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.
- 08-394-25 Service bulletin2025-12-05 · 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
- 9100708 Service bulletin2025-10-29 · Electrical System
- DTC B1E21 is triggered when the TBM Backup Battery is discharged, inactive, or drained. This can happen during the lifetime of the vehicle. TBM should not be replace for B1E21, since there is no fault on TBM. TBM battery is replaceable. Part number of the back-up battery inside TBM is 68597650AA.
What B1E21 means
Source: SAE J2012 / OBD-IIB1E21 is a manufacturer-specific code: the second character is a 1, which under the OBD-II standard hands the definition to whoever built the vehicle. The same code can mean one thing on a Ford and something unrelated on a Hyundai. Any site that prints a single definition for it is guessing.
A stored code names the test that failed, never the part that caused it. It is the starting point of a diagnosis, not its conclusion — the same code has several possible causes and the cheap one is not always right.
Common questions about B1E21
Source: NHTSA files and the OBD-II standardWhy does this page not define B1E21?
Because it cannot be defined honestly. The second character of a trouble code says who owns its meaning, and a 1 or a 3 hands that to the manufacturer. Sites that print one definition for a manufacturer-specific code are showing you one automaker's meaning and hoping it is yours.
Can I keep driving with B1E21 stored?
Nobody can answer that from the code alone, and a site that does is guessing. A steady light means a fault was logged and the car should be checked soon; a flashing light means a severe misfire — slow down and get it seen as soon as possible, because severe misfire can quickly damage the catalytic converter. The safe read of this page is the mileage and the components, not permission.
Does a code mean the car is recalled?
No. Recalls are filed by campaign and matched by VIN, and none of them are triggered by a scan tool. If you want to know whether an open recall applies to one specific vehicle, check the VIN at nhtsa.gov/recalls — that is the only source that settles it.
Why do the counts here differ from other sites?
Because these are not estimates. Every number on this page is a count of documents in NHTSA's own files: manufacturer communications that name the code in their filed summary, and owner complaints that name it in the narrative. We do not model, weight or extrapolate them.
Will clearing the code fix it?
Clearing turns the light off and erases the freeze-frame data a technician would have used to work out what happened. If the condition is still there the code returns, usually within a few drive cycles, and the diagnosis now starts from less information than before.