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Mazda U300A

ELECTRIC PARKING BRAKE (EPB)○ U3004:17 - ACC RELAY CIRCUIT MALFUNCTION○ U0415:00 - MAZDA RADAR CRUISE CONTROL (MRCC)/SMART BRAKE SUPPORT (SBS)○ U0420:00 - MAZDA RADAR CRUISE CONTRO

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceContact a Mazda dealer or qualified service provider for diagnosis, particularly if multiple communication DTCs are present or vehicle communication through DLC-2 is unavailable.
Confidence95%

Quick answer

For certain 2022–2024 US Mazda CX-90 and MX-30 vehicles, verified Mazda communications list U300A:62 as an Electric Parking Brake (EPB) DTC that can appear with multiple other faults when communication is affected by a poor DLC-2 connection. An aftermarket device connected to DLC-2 may spread the female terminals.

This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.

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1. What does U300A mean?

For certain 2022–2024 US Mazda CX-90 and MX-30 vehicles, verified Mazda communications list U300A:62 as an Electric Parking Brake (EPB) DTC that can appear with multiple other faults when communication is affected by a poor DLC-2 connection. An aftermarket device connected to DLC-2 may spread the female terminals.

2. Technical explanation

The supplied evidence identifies the specific listed code as U300A:62, associated with the Electric Parking Brake (EPB). Mazda service communications SA-032-23 and SA-032-23a describe a condition in which a poor DLC-2 connection can prevent communication with the vehicle. The communications state that an aftermarket device may cause DLC-2 female terminals to spread open. U300A:62 may be recorded alongside other module and communication DTCs.

3. What system is affected?

Electric Parking Brake (EPB). The verified bulletin evidence also concerns DLC-2 communication.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

  • U300A:62 may be stored with multiple other DTCs, including U0XXX:00 communication errors.
  • The vehicle may be unable to communicate through DLC-2 due to a poor DLC-2 connection.

6. Possible causes

  • A poor DLC-2 connection.
  • An aftermarket device connected to DLC-2 that may spread the DLC-2 female terminals.

7. Can I still drive the vehicle?

Not yet established by verified evidence.

8. Can I charge the vehicle?

Not yet established by verified evidence.

9. What you can safely do

  • If an aftermarket device is connected to DLC-2, the Mazda communication directs service personnel to photograph it and attach the image to the repair order.
  • Arrange professional diagnosis of the DLC-2 connection and stored DTCs.

10. Step-by-step troubleshooting

  1. Check whether an aftermarket device is connected to DLC-2.
  2. Have a qualified service provider assess DLC-2 connection quality and the stored DTC set. No high-voltage repair procedure is established by the supplied evidence.

11. When to contact service

Contact a Mazda dealer or qualified service provider for diagnosis, particularly if multiple communication DTCs are present or vehicle communication through DLC-2 is unavailable.

12. What the service center may check

  • Check for an aftermarket device connected to DLC-2.
  • Assess whether DLC-2 female terminals have been spread open.
  • Evaluate the poor DLC-2 connection condition described in Mazda communications.
  • Review U300A:62 together with other stored DTCs, including U0XXX:00 communication errors.

13. Possible repair or resolution

  • Not yet established by verified evidence.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Mazda SA-032-23, published May 24, 2023; NHTSA Manufacturer Communication PDF 10237216. It describes poor DLC-2 connection and the possibility that an aftermarket device may spread DLC-2 female terminals; it lists U300A:62 among potentially associated DTCs.
  • Mazda SA-032-23a, published October 11, 2023; NHTSA Manufacturer Communication PDF 10244679. It describes the same DLC-2 connection concern and lists U300A:62 among potentially associated DTCs.

16. Recall information

  • Not yet established by verified evidence.

17. Official manufacturer information

Official NHTSA-hosted Mazda communications: https://static.nhtsa.gov/odi/tsbs/2023/MC-10237216-0001.pdf and https://static.nhtsa.gov/odi/tsbs/2023/MC-10244679-0001.pdf. Verified applicability: 2022–2024 Mazda CX-90 and MX-30, US.

19. Frequently asked questions

What does U300A mean in the supplied Mazda evidence?

The supplied Mazda communications list U300A:62 as an Electric Parking Brake (EPB) DTC.

Can an aftermarket OBD/DLC-2 device be relevant?

Yes. The communications state that an aftermarket device may cause DLC-2 female terminals to spread open, contributing to a poor DLC-2 connection.

Does this evidence prove an EPB component failure?

No. The verified evidence associates U300A:62 with a DLC-2 communication-related condition but does not establish an EPB component failure.

Is it safe to drive or charge?

Not yet established by verified evidence.

20. Sources & verification

ReferenceVerified
Mazda U300A: ELECTRIC PARKING BRAKE (EPB)○ U3004:17 - ACC RELAY… | EV Diagnostics