C0135

Code

Generic C — Chassis

ABS wheel speed sensor circuit malfunction

Brand: Generic

Type: C — Chassis

Views: UK: 14 EN: 19 RU: 14

AI status

Completed

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Page language: EN

Causes

Damaged or corroded wheel speed sensor
Damaged tone ring/reluctor (missing or cracked teeth)
Wiring harness damage (open, short to ground, short to Vb, or high resistance)
Poor connector contact or corrosion at sensor connector
Contaminated sensor face (metal debris, brake dust)
Failed wheel bearing allowing sensor misalignment

Symptoms

ABS warning lamp (and possibly traction/stability lamp) illuminated
ABS/traction control inactive or unavailable
Brake pedal feel usually normal for basic braking, but ABS may not function
Occasional or constant diagnostic trouble code memory for wheel speed sensor
Erratic speedometer/vehicle stability behavior on some vehicles

What to check

Read freeze frame and live wheel speed sensor data with a scan tool; compare all four wheel speed readings at slow roll
Visual inspection of sensor, tone ring, harness, and connector for damage or contamination
Wiggle test wiring/backprobe connector while observing live data for intermittent changes
Measure sensor circuit resistance (for passive sensors) and compare to spec in service manual
Measure sensor output while spinning the wheel (AC voltage for VR or square wave/frequency for active sensors) with DMM or oscilloscope
Check sensor supply voltage and ground for active sensors (typically reference +V and ground) with key on

Signal parameters

Passive (VR) sensor: generates AC voltage proportional to wheel speed; low-speed amplitude may be ~0.1–1.5 VAC and increases with speed (values vary by vehicle)
Active (Hall/electronic) sensor: provides a pulsed digital/square wave; typical logic levels are 0–5 V (some systems use different reference voltages)
Typical passive sensor DC resistance: often in the hundreds to a few thousand ohms; consult vehicle service manual for exact spec
Signal frequency increases with wheel rotational speed; compare frequency from suspect wheel to a known-good wheel

Diagnostic algorithm

Retrieve ABS codes and freeze-frame data with a scan tool; note which wheel is affected.
Perform a visual inspection of the suspect wheel hub area, tone ring, sensor mounting, connector and harness for obvious damage or contamination.
Clean sensor and tone ring if contaminated, reseat connector, clear codes and road test to see if code returns.
With wheel off the ground and supported safely, spin the wheel while monitoring live wheel speed data; compare to other wheels for amplitude/frequency or dropouts.
For passive sensors: measure resistance between sensor terminals (engine off) and measure AC output while spinning. For active sensors: check reference voltage, signal output (with scope or DMM if possible) and ground at the connector.
Wiggle the harness and connector while observing live data for intermittent faults. Inspect wiring for chafe points, repair or replace damaged wiring as needed.
If sensor and wiring check good, test or bench-check replacement sensor before installation. If wiring and sensor test good, check ABS module power/ground and related modules for faults.
After repair, clear codes and perform a calibrated road test and re-scan to verify code does not return.

Likely causes

Connector corrosion or bent pins at the sensor
Sensor air gap too large or misaligned due to bearing / mounting damage
Wire chafing against suspension components causing intermittent open/short
Tone ring damage from road debris or rust buildup
Failed passive (VR) or active (Hall/diamond) sensor element

Fault status

⚠️ Status

ABS control module detected an abnormal wheel speed sensor circuit signal (open/short/intermittent or implausible reading). ABS/traction functions for the affected wheel may be disabled until the issue is resolved.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.5 hours