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B0123 — Pedestrian Alert Speaker B

Generic OBD-II · all makesBody

Code B0123 indicates a malfunction in the Pedestrian Alert System (PAS) specifically related to Speaker B. The system has detected an electrical abnormality, such as an open or short circuit, preventing the speaker from emitting the required low-speed warning sound.

Symptoms

What causes it — most likely first

1. Failed Speaker B

The internal voice coil or diaphragm of the speaker has failed or burned out.

2. Wiring Harness Damage

Wires leading to Speaker B are frayed, broken, or chewed by rodents due to their exposed location in the chassis.

3. Corroded Connectors

Moisture and road salt have caused corrosion at the speaker plug, increasing electrical resistance.

4. Water Intrusion

Water has entered the speaker housing, causing an internal short circuit.

5. Control Module Failure

The internal driver circuit within the PAS or body control module has failed.

How it's diagnosed

  1. Inspect Speaker B and its surrounding area for visible physical damage or debris.
  2. Verify the electrical connector is securely seated and free of corrosion.
  3. Measure the resistance (ohms) of Speaker B using a multimeter to verify it is within factory specifications.
  4. Perform a continuity test on the wiring harness from the speaker connector back to the control module.
  5. Use a signal generator or known-good speaker to verify the module is sending the correct output signal.
  6. Clear the code and perform a system self-test to see if the fault returns.

Code facts & related codes

SystemBody
StandardizationSAE generic — identical on every make
Related codesB0120 — Fluid Reservoir Level Sensor EB0121 — Fluid Reservoir Level Sensor FB0122 — Pedestrian Alert SpeakerB0124 — Night Vision CameraB0125 — Night Vision Control ModuleB0126 — Driver Monitoring Camera

Frequently asked

Will this code prevent my car from passing an inspection?

Depending on local regulations and the vehicle's safety requirements, a malfunctioning pedestrian alert system may be flagged during a safety inspection.

Should I replace the control module if I see this code?

No. Because these speakers are mounted low in the vehicle and exposed to the elements, the speaker itself or the wiring is significantly more likely to fail than the control module.

Does this affect the braking or steering of the vehicle?

No, the Pedestrian Alert System is an acoustic warning system and does not integrate with the vehicle's primary mechanical driving or braking systems.