A damaged or chafed wire in the left front sensor harness, usually where it flexes near the strut or passes through a clip.; Corrosion or poor pin tension inside the left front sensor connector or the ABS module connector.; Debris, metal shavings, or rust buildup on the sensor tip or the tone ring, disturbing the air gap.; A cracked or missing tone ring tooth, or a tone ring that has separated from the hub.; An internally failing wheel speed sensor that still tests fine when cold but drops out when hot or vibrating.; Excessive wheel bearing play or hub runout that changes the sensor air gap as the wheel turns.; A faulty ABS control module input circuit, which is the least common but most expensive possibility.

DTC codes / C06xx · Brakes, steering and suspension / C0655

C0655Left Front Wheel Speed Sensor B Intermittent/Erratic

Q: What does code C0655 mean?

Left Front Wheel Speed Sensor B Intermittent/Erratic. C0655 means the antilock braking system (ABS) module has detected an intermittent or erratic signal from the left front wheel speed sensor circuit B, which is the second signal path on that corner in systems that use dual sensors or a redundant output. The computer sets this code when the signal drops out, jumps, or becomes inconsistent for a fraction of a second while the vehicle is moving, so the ABS cannot trust that wheel's speed reading.

C0655 means the antilock braking system (ABS) module has detected an intermittent or erratic signal from the left front wheel speed sensor circuit B, which is the second signal path on that corner in systems that use dual sensors or a redundant output. The computer sets this code when the signal drops out, jumps, or becomes inconsistent for a fraction of a second while the vehicle is moving, so the ABS cannot trust that wheel's speed reading.

SystemChassis

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaBrakes, steering and suspension

Symptoms you may notice

The ABS warning light is illuminated steadily, and on many vehicles the traction control and stability control lights come on with it.
Often no symptoms besides the warning light, because the fault is intermittent and the base brakes still work normally.
The ABS may activate briefly or pulse the pedal at low speeds when it should not, especially during parking-lot maneuvers.
Traction control or stability control may cut in unexpectedly or shut off entirely while driving.
A wheel-speed-related message may appear on the driver information display, and cruise control may refuse to engage.
In rare cases the speedometer or odometer behaves erratically if the module uses this sensor for vehicle speed.

Common causes, most likely first

A damaged or chafed wire in the left front sensor harness, usually where it flexes near the strut or passes through a clip.
Corrosion or poor pin tension inside the left front sensor connector or the ABS module connector.
Debris, metal shavings, or rust buildup on the sensor tip or the tone ring, disturbing the air gap.
A cracked or missing tone ring tooth, or a tone ring that has separated from the hub.
An internally failing wheel speed sensor that still tests fine when cold but drops out when hot or vibrating.
Excessive wheel bearing play or hub runout that changes the sensor air gap as the wheel turns.
A faulty ABS control module input circuit, which is the least common but most expensive possibility.

How to diagnose and fix it

Scan all modules for codes and record freeze-frame data, then clear the code and road test to confirm whether C0655 returns and under what conditions.
Inspect the left front sensor harness and connector for chafing, corrosion, and loose pins, and wiggle-test the wiring while watching live wheel-speed data.
Remove the sensor and check the tip and tone ring for metal debris, rust, cracks, or missing teeth, then clean and reinstall it with the correct air gap.
Measure sensor resistance and compare it with the right front sensor, then check for an intermittent open or short by flexing the harness.
Check wheel bearing play and hub runout on the left front corner, since a loose bearing can mimic a failing sensor.
If the sensor and wiring test good, scope the signal at the ABS module connector to rule out a module input fault before replacing the module.
After repair, clear codes, perform any required steering-angle or wheel-speed calibration, and road test at highway speed to confirm the fix.

Why intermittent wheel speed codes fool everyone

A sensor that passes a static resistance test can still set C0655, because the fault often only appears when the harness flexes over bumps or the sensor heats up during a drive.
Metal debris stuck to the sensor magnet is one of the most common causes on vehicles driven on gravel or near construction sites, and it is fixed by cleaning rather than replacement.
A worn wheel bearing changes the air gap as the wheel rotates and can trigger an erratic signal that looks exactly like a bad sensor, so always check bearing play before condemning the sensor.
The B designation means this is a second signal path, so on some vehicles the primary sensor circuit can be fine while a redundant output or shared ground is the actual problem.
An intermittent C0655 that only appears in wet weather usually points to a connector seal or harness chafe letting moisture into the circuit, not to the sensor itself.

Can I keep driving with C0655?

The vehicle remains safe to drive at normal speeds because the base hydraulic brakes work, but the ABS and stability control may not assist you in an emergency stop or slippery conditions. Avoid hard braking, towing, and wet or icy roads until the fault is repaired, and treat the warning light as a reminder to get it diagnosed promptly.

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.