B1252 on the 2026 Mazda Mazda3
The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.
This code is specific to a manufacturer and is not described here. Its meaning is in the manufacturer's service information.
| SA-012-26d | 2026-10-01. Service bulletin. 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'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 REPAIR PROCEDURE 1. Verify the concern. 2. Check if any of the following DTCs are 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 Are the following DTCs stored? YES: Proceed to next step. NO: This service information does not apply. Continue troubleshooting using MGSS. |
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| SA-012-26c | 2026-09-04. Service bulletin. This Service Alert supersedes the previously issued SA(s) listed below. The changes are noted in Red. SA-012/26 04/17/26, 03/04/26 and 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'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 REPAIR PROCEDURE 1. Verify the concern. 2. Check if any of the following DTCs are 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-012-26b | 2026-05-04. Service bulletin. 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 WITH EMERGENCY CALL UNIT/TELEMATICS COMMUNICATION UNIT REPAIR PROCEDURE 1. Verify the concern. 2. Check if any of the following DTCs are 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 Are the following DTCs stored? YES: Proceed to next step. • NO: This service information does not apply. Continue troubleshooting using MGSS. • 3. Check for electrical devices in the vehicle such as a device connected to USB hub, Dash Cam, Insurance Device, FasTrak........ect. Are there any customer electrical devices in the vehicle? YES: Document customer device used, then go to the next step. • NO: Go to the next step. • 4. Clear the DTC's |
| SA-012-26a | 2026-04-02. Service bulletin. 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'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 REPAIR PROCEDURE 1. Verify the concern. 2. Check if any of the following DTCs are 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 Are the following DTCs stored? YES: Proceed to next step. NO: This service information does not apply. Continue troubleshooting using MGSS. 3. Check for electrical devices in the vehicle such as a device connected to USB hub, Dash Cam, Insurance Device, FasTrak........ect. Are there any customer electrical devices in the vehicle? YES: Document customer device used, then go to the next step. NO: Go to the next step. 4. Check for a Navi SD Card. Is the vehicle equipped with a Navi SD Card? YES: Replace the Navi SD Card. NO: Go to next step. 5. Complete the Dealer Connected Vehicle Questionnaire. 6. Collect CMU log data. Go to Infotainment/TCU --> Collecting CMU Log Data --> CMU Log Data Retrieval Instructions 7. Collect TCU log data. Go to Infotainment/TCU --> TCU Log Data Retrieval Instructions --> CMU Log Data Retrieval Instructions 8. Contact Hotline for additional assistance. 9. Release the vehicle to the customer. NOTE: This concern is currently under investigation |
| SA-012-26 | 2026-03-04. Service bulletin. 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: 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-060-25 | 2026-01-03. Service bulletin. 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 |
6 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.