Damaged or disconnected wiring harness at the pedestrian alert speaker, often from road debris or curb contact; Corroded or loose speaker connector pins due to water intrusion or road salt exposure; Failed pedestrian alert speaker, typically from moisture ingress or vibration fatigue; Open or shorted circuit in the harness between the sound module and the speaker; Internal fault in the body control module or dedicated pedestrian alert sound module; Blown fuse or poor ground connection serving the pedestrian alert circuit; Aftermarket modifications or accident repairs that disturbed the speaker wiring

DTC codes / B01xx · Airbags, seats, doors, lights and comfort systems / B0123

B0123Pedestrian Alert Speaker B

Q: What does code B0123 mean?

Pedestrian Alert Speaker B. B0123 indicates a fault in the pedestrian alert speaker circuit, which is the external sound generator that hybrid and electric vehicles use to warn pedestrians at low speeds. The body control module or dedicated sound module has detected an open circuit, short to ground, short to battery voltage, or an abnormal speaker resistance on the output to that speaker.

B0123 indicates a fault in the pedestrian alert speaker circuit, which is the external sound generator that hybrid and electric vehicles use to warn pedestrians at low speeds. The body control module or dedicated sound module has detected an open circuit, short to ground, short to battery voltage, or an abnormal speaker resistance on the output to that speaker.

SystemBody

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

A warning light or message on the instrument cluster indicating a pedestrian alert system fault
No audible pedestrian warning sound when the vehicle is moving slowly or in reverse
A weak, distorted, or intermittent warning tone from the external speaker
The warning sound may default to a louder or different tone as a failsafe
Often no symptoms besides the warning light, because the speaker only operates at low speeds and many drivers never notice its absence
Related driver assistance or hybrid system messages may appear if the module disables the alert function

Common causes, most likely first

Damaged or disconnected wiring harness at the pedestrian alert speaker, often from road debris or curb contact
Corroded or loose speaker connector pins due to water intrusion or road salt exposure
Failed pedestrian alert speaker, typically from moisture ingress or vibration fatigue
Open or shorted circuit in the harness between the sound module and the speaker
Internal fault in the body control module or dedicated pedestrian alert sound module
Blown fuse or poor ground connection serving the pedestrian alert circuit
Aftermarket modifications or accident repairs that disturbed the speaker wiring

How to diagnose and fix it

Verify the code with a scan tool and check for any related body or hybrid control module codes before touching hardware
Inspect the pedestrian alert speaker and its connector for physical damage, corrosion, or water intrusion
Check the pedestrian alert circuit fuse and confirm the sound module has good power and ground
Measure resistance across the speaker terminals and compare with the manufacturer's specification to confirm speaker condition
Perform a wiggle test on the harness while monitoring speaker resistance or command the alert sound with a scan tool to catch intermittent faults
Repair or replace damaged wiring, terminals, or the speaker as indicated by the test results
Clear the code and verify the pedestrian alert sound operates correctly at low speed and in reverse

Why the pedestrian alert speaker fails quietly

Many drivers never realize the pedestrian alert speaker has failed because the warning sound is only required at low speeds and is easily masked by road noise or the radio.
A common misdiagnosis is replacing the sound module when the real problem is a corroded speaker connector behind the front bumper that sees constant water and salt spray.
The code can be set by a momentary open circuit during a bump or car wash, so an intermittent history code may not indicate a hard failure until the fault is reproduced.
Some vehicles use the same speaker for both the pedestrian alert and other audible warnings, so a failure can also affect chime or alarm functions without a separate code.
After a collision repair or bumper replacement, the speaker or its harness is frequently left disconnected or pinched, setting B0123 even though the component itself is good.

Can I keep driving with B0123?

The vehicle remains safe to drive because the pedestrian alert is a warning aid rather than a safety-critical system, but you should avoid low-speed areas with pedestrians until repaired. Use extra caution in parking lots, driveways, and crosswalks where the missing sound could surprise someone.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.