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Mazda B1B38

04 Front ultrasonic sensor (RH) signal circuit malfunction B1B38:49 Front ultrasonic sensor (RH) power supply circuit malfuncti on B1B40:04 Front corner ultrasonic sensor (LH) sign

DriveNot yet established by verified evidence.
ChargeNot yet established by verified evidence.
ServiceMazda service is recommended for diagnosis, particularly if the code followed ultrasonic-sensor replacement during body or paint repair. Urgency is not established by verified evidence.
Confidence95%

Quick answer

For a 2022 Mazda MX-30 in the US, DTC B1B38 is identified in Mazda/NHTSA service communication 09-026-23 as a front ultrasonic sensor (right-hand) signal-circuit malfunction (:04) or power-supply-circuit malfunction (:49). The communication concerns codes stored after front and/or rear ultrasonic sensor replacement during body or paint repair.

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 B1B38 mean?

For a 2022 Mazda MX-30 in the US, DTC B1B38 is identified in Mazda/NHTSA service communication 09-026-23 as a front ultrasonic sensor (right-hand) signal-circuit malfunction (:04) or power-supply-circuit malfunction (:49). The communication concerns codes stored after front and/or rear ultrasonic sensor replacement during body or paint repair.

2. Technical explanation

Verified evidence distinguishes two B1B38 fault variants: B1B38:04, front ultrasonic sensor (RH) signal circuit malfunction; and B1B38:49, front ultrasonic sensor (RH) power supply circuit malfunction. The supplied evidence does not establish a further diagnostic sequence, component-level root cause, or repair procedure.

3. What system is affected?

Front ultrasonic sensor system; the exact broader system name is not established by verified evidence.

4. How serious is this code?

Not yet established by verified evidence.

5. Symptoms you may notice

  • A B1B38 fault code may be stored after replacement of front and/or rear ultrasonic sensor(s) during body or paint repair, according to Mazda communication 09-026-23.
  • Other driver-visible symptoms are not yet established by verified evidence.

6. Possible causes

  • The verified communication addresses B1B38 stored after front and/or rear ultrasonic sensor replacement during body or paint repair.
  • A specific underlying cause is not yet established by verified evidence.

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

  • Record the complete DTC, including its suffix (:04 or :49), before service.
  • Tell the service provider whether front or rear ultrasonic sensors were replaced during recent body or paint work.
  • Use a Mazda service provider to diagnose the stored code. Do not attempt electrical circuit repair based on the supplied evidence.

10. Step-by-step troubleshooting

  1. Confirm whether the stored code is B1B38:04 or B1B38:49.
  2. Review recent body or paint repair history, including replacement of front and/or rear ultrasonic sensors.
  3. Refer the vehicle to a Mazda service provider; further troubleshooting steps are not established by verified evidence.

11. When to contact service

Mazda service is recommended for diagnosis, particularly if the code followed ultrasonic-sensor replacement during body or paint repair. Urgency is not established by verified evidence.

12. What the service center may check

  • Confirm the exact B1B38 suffix: :04 denotes the front ultrasonic sensor (RH) signal circuit, while :49 denotes its power supply circuit.
  • Review whether front and/or rear ultrasonic sensors were replaced during body or paint repair.
  • Additional service checks are not yet established by verified evidence.

13. Possible repair or resolution

  • A verified repair resolution is not provided in the supplied evidence.
  • The supplied communication specifically concerns DTCs stored after ultrasonic-sensor replacement during body or paint repair.

14. Affected vehicles

15. Related TSBs / service bulletins

  • Mazda service communication 09-026-23, published through NHTSA on June 28, 2023 (NHTSA manufacturer communication PDF 10238672). It lists B1B38:04 and B1B38:49 among ultrasonic-sensor DTCs that may be stored after front and/or rear ultrasonic sensor replacement during body or paint repair.

16. Recall information

  • No recall information is established by the supplied verified evidence.

17. Official manufacturer information

Official source: NHTSA Manufacturer Communication PDF 10238672, Mazda communication 09-026-23: https://static.nhtsa.gov/odi/tsbs/2023/MC-10238672-0001.pdf

19. Frequently asked questions

What does Mazda code B1B38 mean?

For the covered vehicle, B1B38:04 means front ultrasonic sensor (RH) signal circuit malfunction, and B1B38:49 means front ultrasonic sensor (RH) power supply circuit malfunction.

Which vehicle is covered by the supplied evidence?

The verified applicability is the US-market 2022 Mazda MX-30.

Is B1B38 linked to body or paint work?

Mazda communication 09-026-23 addresses B1B38 among DTCs stored after front and/or rear ultrasonic sensor replacement during body or paint repair. It does not establish that all B1B38 occurrences have that history.

Can I drive or charge with B1B38?

Not yet established by verified evidence.

20. Sources & verification

Verified
Mazda B1B38: 04 Front ultrasonic sensor (RH) signal circuit… | EV Diagnostics