B12C5 on Honda vehicles
B12C5 is named on 8 Honda model years (2016–2018): 16 manufacturer filings and 8 owner reports in NHTSA’s files, across Pilot, HR-V, Ridgeline, Fit.
Which Honda model years name B12C5
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2016 Honda Pilot | Electrical System | 2 | 3 |
| 2016 Honda HR-V | Electrical System | 2 | 2 |
| 2017 Honda HR-V | Engine | 2 | 1 |
| 2017 Honda Pilot | Engine | 2 | 1 |
| 2017 Honda Ridgeline | Equipment Adaptive/Mobility | 2 | 1 |
| 2018 Honda HR-V | Electrical System | 2 | — |
| 2017 Honda Fit | Electrical System | 2 | — |
| 2016 Honda Fit | Engine | 2 | — |
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.
What Honda owners said
Source: NHTSA complaint databaseOwners’ own words, scrubbed of anything identifying. Unverified reports filed with NHTSA — what was said, not a finding that it was true.
is fully aware of this systemic defect, having issued Technical Service Bulletin TSB 20-116 (Diagnostic Trouble Code DTC B12C5) specifically addressing ignition start/stop switch failure
Honda issued Service Bulletin 20-117 regarding a Warranty Extension for the 2016–2017 Pilot and 2017 Ridgeline addressing a Keyless Start System Error with DTC B12C5
The dealer confirmed that this was in no relation to the recent recall of the Ridgeline Keyless Start System Error with DTC B12C5 and that the Keyless System Main Control Unit failed, part number 38320-T6Z-A21
Honda filings that name B12C5
Source: NHTSA manufacturer communicationsBulletins and campaigns Honda filed with NHTSA whose summary names B12C5. Quote the document number at the service desk — it is a diagnosis the maker has already written down.
- A20-117 Service bulletin2020-12-09 · Electrical System
- Service Bulletin - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch Failure) is stored. American Honda is extending the warranty for the keyless start system on these vehicles to 9 years from the original date of purchase or 125,000 miles, whichever comes first.
- ONLY9302162021 Service bulletin2021-02-16 · Equipment
- Owner Notification Letter - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, the MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch Failure) is stored. American Honda is extending the warranty on the engine start/stop switch to 9 years from the original date of purchase or 125,000 miles, whichever comes first.
- A20-116 Service bulletin2020-12-09 · Electrical System
- Service Bulletin - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch Failure) is stored. American Honda is extending the warranty for the keyless start system on these vehicles to 9 years from the original date of purchase or 125,000 miles, whichever comes first.
- ONLV9202162021 Service bulletin2021-02-16 · Engine And Engine Cooling
- Owner Notification Letter - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, the MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch Failure) is stored. American Honda is extending the warranty on the engine start/stop switch to 9 years from the original date of purchase or 125,000 miles, whichever comes first.
- A20-098 Service bulletin2020-12-09 · Electrical System
- Service Bulletin - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch Failure) is stored. American Honda is extending the warranty for the keyless start system on these vehicles to 9 years from the original date of purchase or 125,000 miles, whichever comes first.
- ONLV9002162021 Service bulletin2021-02-16 · Engine And Engine Cooling
- Owner Notification Letter - The vehicle may not start upon first press of the ENGINE START/STOP button. Also, the MID displays the error message KEYLESS START SYSTEM ERROR, and DTC B12C5 (Engine Start/Stop Switch Failure) is stored. American Honda is extending the warranty on the engine start/stop switch to 9 years from the original date of purchase or 125,000 miles, whichever comes first.
What B12C5 means
Source: SAE J2012 / OBD-IIB12C5 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. The record above is what Honda and its owners have filed about it; the code’s page across every make has the whole file.
Common questions
Source: NHTSA files and the OBD-II standardIs B12C5 a known problem on Honda vehicles?
It is a documented one: NHTSA's files hold 16 manufacturer filings and 8 owner reports naming B12C5 on 8 Honda model years (2016–2018). Whether it is a problem on one particular car is a diagnosis, not a count — but a bulletin that names the code on your model year is the place to start.
Which Honda models does B12C5 appear on most?
2016 Pilot (5 documents), 2016 HR-V (4 documents), 2017 HR-V (3 documents).
Does B12C5 on a Honda mean it is recalled?
No. Recalls are filed by campaign and matched by VIN; no recall is triggered by a scan tool. Check the VIN at nhtsa.gov/recalls, or open the model year's page here for the campaigns filed against it.