B1252 on Mazda vehicles
B1252 is named on 16 Mazda model years (2019–2026): 121 manufacturer filings and 0 owner reports in NHTSA’s files, across CX-50, CX-70, CX-90, CX-30, Mazda3.
Which Mazda model years name B1252
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2026 Mazda CX-50 | Electrical System | 12 | — |
| 2025 Mazda CX-50 | Electrical System | 12 | — |
| 2026 Mazda CX-70 | Electrical System | 11 | — |
| 2026 Mazda CX-90 | Electrical System | 11 | — |
| 2025 Mazda CX-70 | Electrical System | 11 | — |
| 2025 Mazda CX-90 | Electrical System | 11 | — |
| 2024 Mazda CX-90 | Electrical System | 10 | — |
| 2026 Mazda CX-30 | Electrical System | 6 | — |
| 2026 Mazda Mazda3 | Electrical System | 6 | — |
| 2025 Mazda CX-30 | Electrical System | 6 | — |
| 2025 Mazda Mazda3 | Electrical System | 6 | — |
| 2024 Mazda CX-30 | Electrical System | 5 | — |
| 2024 Mazda Mazda3 | Electrical System | 5 | — |
| 2020 Mazda CX-30 | Electrical System | 3 | — |
| 2020 Mazda Mazda3 | Electrical System | 3 | — |
| 2019 Mazda Mazda3 | Electrical System | 3 | — |
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.
Mazda filings that name B1252
Source: NHTSA manufacturer communicationsBulletins and campaigns Mazda filed with NHTSA whose summary names B1252. Quote the document number at the service desk — it is a diagnosis the maker has already written down.
- SA-060-25 Service bulletin2025-12-17 · Unknown Or Other
- Some customers may experience a message "TCU Malfunction. Have the Vehicle Inspected" in the instrument cluster. The following DTC's may be stored: B1252:87-8B:TCU - COMMUNICATION ERROR WITH CONNECTIVITY MASTER UNIT (CMU) • U0198:00-03:CMU - COMMUNICATION ERROR WITH EMERGENCY CALL UNIT/TELEMATICS COMMUNICATION UNIT
- SA-012-26 Service bulletin2026-02-27 · Unknown Or Other
- This Service Alert supersedes the previously issued SA(s) listed below. The changes are noted in Red. SA-060/25 12/16/25 Some customers may experience a message "TCU Malfunction. Have the Vehicle Inspected" in the instrument cluster. Additional symptoms that may occur: Connected Vehicle One Time Passcode (OTP) may fail. Connected Vehicle Remote functions may fail. The following DTC's may be stored
- SA-012-26a Service bulletin2026-03-04 · Electrical System
- This Service Alert supersedes the previously issued SA(s) listed below. The changes are noted in Red. SA-012/26 02/26/2026 DESCRIPTION Some customers may experience a message "TCU Malfunction. Have the Vehicle Inspected" in the instrument cluster. Additional symptoms that may occur: Connected Vehicle One Time Passcode (OTP) may fail. Connected Vehicle Remote functions may fail. The following DTC'
- SA-012-26b Service bulletin2026-04-18 · Electrical System
- Some customers may experience a message "TCU Malfunction. Have the Vehicle Inspected" in the instrument cluster. Additional symptoms that may occur: Connected Vehicle One Time Passcode (OTP) may fail. • Connected Vehicle Remote functions may fail. • The following DTC's may be stored: B1252:87-8B:TCU - COMMUNICATION ERROR WITH CONNECTIVITY MASTER UNIT (CMU) • U0198:00-03:CMU - COMMUNICATION ERROR W
- SA-029-20 Service bulletin2020-02-25 · Electrical System
- Some customers may experience a "IN-VEHICLE NETWORK MALFUNCTION" warning message in the instrument cluster with one or more of the following DTC's stored: B119F:01 TCU - Tel antenna No. 1 malfunction B1252:87 TCU - Communication error with connectivity master unit (CMU) U0156:00 VCM - Communication error with connectivity master unit (CMU) U0156:00 BCM - Communication error with connectivity mast
- SA-029-20a Service bulletin2020-04-08 · Electrical System
- Some customers may experience a "IN-VEHICLE NETWORK MALFUNCTION" warning message in the instrument cluster with one or more of the following DTC's stored: ï· B119F:01 TCU - Tel antenna No. 1 malfunction ï· B1252:87 TCU - Communication error with connectivity master unit (CMU) ï· U0156:00 VCM - Communication error with connectivity master unit (CMU) ï· U0156:00 BCM - Communication error with c
- SA-0290-20c Service bulletin2020-06-05 · Equipment — Electrical
- Some customers may experience a "IN-VEHICLE NETWORK MALFUNCTION" warning message in the instrument cluster with one or more of the following DTC's stored: ï· B119F:01 TCU - Tel antenna No. 1 malfunction ï· B1252:87 TCU - Communication error with connectivity master unit (CMU) ï· U0156:00 VCM - communication error with connectivity master unit (CMU) ï· U0156:00 BCM - Communication error with
What B1252 means
Source: SAE J2012 / OBD-IIB1252 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 Mazda 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 B1252 a known problem on Mazda vehicles?
It is a documented one: NHTSA's files hold 121 manufacturer filings and 0 owner reports naming B1252 on 16 Mazda model years (2019–2026). 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 Mazda models does B1252 appear on most?
2026 CX-50 (12 documents), 2025 CX-50 (12 documents), 2026 CX-70 (11 documents).
Does B1252 on a Mazda 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.