Damaged, chafed or corroded wiring or connector at the left front wheel speed sensor, often from hub or suspension movement; Faulty left front wheel speed sensor (internal fault or intermittent signal); Dirt, metal debris or corrosion on the sensor tip or sensor mounting, or a loose sensor; Damaged, cracked or rusty tone ring or magnetic encoder in the wheel bearing, or a worn wheel bearing causing excess play; Incorrect air gap or sensor fitment after previous work on the hub, brakes or suspension; Poor power or earth supply to the ABS module, or a fault in the module itself.

C0655

Left Front Wheel Speed Sensor B Intermittent/Erratic.

Generic
Chassis
Generic code
Medium severity

How this code is built

C: SystemChassis
0: Defined bySAE, the same on every car
6: AreaChassis area 6
55: FaultThe specific fault in that area

What it means

C0655 is a generic chassis code meaning the ABS/traction control module has seen an intermittent or erratic signal from the left front wheel speed sensor 'B' circuit. The signal drops out, jumps or disagrees with the other wheel speeds and vehicle speed, so the module sets the fault. Which sensor or circuit is labelled 'B' depends on the manufacturer and model, so check the vehicle-specific data.

Symptoms

ABS warning light on
Traction control or stability control warning light on, or those systems disabled
Speedometer needle flickering or reading wrongly on some models
ABS or traction control activating when it should not, or not working when needed
Fault appearing and disappearing, often with road bumps or steering lock
Cruise control unavailable on some models

Possible causes

Damaged, chafed or corroded wiring or connector at the left front wheel speed sensor, often from hub or suspension movementlikely
Faulty left front wheel speed sensor (internal fault or intermittent signal)likely
Dirt, metal debris or corrosion on the sensor tip or sensor mounting, or a loose sensorpossible
Damaged, cracked or rusty tone ring or magnetic encoder in the wheel bearing, or a worn wheel bearing causing excess playpossible
Incorrect air gap or sensor fitment after previous work on the hub, brakes or suspensionpossible
Poor power or earth supply to the ABS module, or a fault in the module itselfrare

How to diagnose

Read all stored codes and freeze frame data, noting vehicle speed and conditions when the fault set, and check for other wheel speed codes
Inspect the left front sensor wiring and connector from the sensor to the body for chafing, kinks, water ingress, corrosion and a secure fit
Check the sensor is fitted correctly and secure, and that the tip and mounting are free of dirt, debris and rust
Inspect the tone ring or encoder for damage, missing teeth, contamination or rust, and check the wheel bearing for play or roughness
With a scan tool, view live wheel speed data on a test drive and compare the left front with the other wheels for dropouts or spikes
Wiggle test the harness and connector with the live data showing, watching for signal loss
Measure sensor resistance, supply voltage or signal output as per the manufacturer's specification for that model, as the sensor type varies
Check the ABS module's power and earth supplies and connector if the wheel circuit tests good

How to fix

Repair or replace damaged wiring or the connector, and secure the harness away from moving parts
Replace the left front wheel speed sensor if it fails testing or shows an intermittent signal
Clean the sensor and mounting, and refit it correctly to the specified fitment
Replace the wheel bearing or tone ring/encoder if it is damaged, worn or contaminated
Repair power or earth supply faults, and only consider the ABS module after all other causes are ruled out

Can I keep driving?

Medium severity

The car normally brakes as usual without ABS and stability control assistance, so it can be driven carefully for a short time, but expect reduced grip control in wet or slippery conditions. Book it in soon, and avoid driving hard until it is repaired.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.