C0320

Code

Generic C — Chassis

ABS wheel speed sensor circuit malfunction

Brand: Generic

Type: C — Chassis

Views: UK: 10 EN: 21 RU: 16

AI status

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Page language: EN

Causes

Open or short in the wheel speed sensor wiring harness
Corroded, loose, or damaged sensor connector
Failed wheel speed sensor (Hall-effect or VR sensor)
Damaged or missing tone ring/reluctor (broken, contaminated, or magnetized)
Excessive wheel bearing play or debris affecting sensor gap
Poor ground or reference voltage feeding the sensor

Symptoms

ABS warning lamp illuminated on dash (may also light traction control/ESC lamp)
ABS and/or traction control systems may be disabled
Possible intermittent ABS activation or false ABS events
Speedometer usually unaffected (vehicle speed sensor is different), unless integrated systems share inputs
Unusual noise or roughness from wheel area if tone ring or bearing is damaged

What to check

Read live data with a scan tool: compare wheel speed readings while rotating each wheel — a faulty sensor often shows zero, erratic, or no signal for that wheel
Perform visual inspection of sensor, tone ring, and wiring for damage, contamination, rubbing, or missing teeth
Check connector pins for corrosion, bent pins, or poor mating; unplug/replug and inspect
Measure sensor resistance (ohms) and compare to manufacturer spec; look for open/short
Check sensor output with oscilloscope while wheel is rotated (preferred) or with multimeter for AC voltage on VR sensors or DC switching on Hall sensors
Back-probe reference voltage and ground at the sensor connector (Hall sensors often require ~5V reference)

Signal parameters

Variable-reluctance (VR) sensor: AC sine-like pulses; amplitude increases with wheel speed — typically from a few tens of mV at very low speed to ~0.05–2.5 VAC or higher depending on system and speed
VR sensor DC resistance (typical range): ~800–3000 ohms (manufacturer-specific)
Hall-effect sensor: digital square-wave output referenced to supply; typically 0–5 V (or 0.5–4.5 V) switching levels with ~5 V reference supply
Pulse frequency proportional to wheel speed and number of tone-ring teeth (frequency increases linearly with speed)
Expected behavior: clean, consistent pulses or square waves with no dropouts or irregular amplitude when wheel is rotated

Diagnostic algorithm

Retrieve freeze frame and live data with scan tool; note which wheel shows fault and when it occurs.
Visually inspect the suspect wheel sensor, connector, tone ring and wiring for obvious damage, contamination, or missing teeth.
With the connector disconnected, measure sensor resistance; compare to spec. If open/short, replace sensor.
Reconnect and back-probe the connector while spinning the wheel. For VR sensors measure AC output with scope/multimeter; for Hall sensors confirm reference voltage (≈5V) and switching output between ~0–5V.
Wiggle the harness and connectors while monitoring live data or signal to detect intermittent faults.
Check continuity between the sensor connector and the ABS module pins; repair any shorts/opens or damaged shielding/grounds.
Inspect/repair tone ring: remove debris, correct alignment, or replace if teeth are damaged or missing.
If sensor and wiring tests are good but the code persists, check ABS module input circuits and communication; consult manufacturer procedures for module testing.
Clear codes and road-test to verify repair; confirm no reappearance of code and that ABS/ESC operate normally.

Likely causes

Damaged or contaminated wheel speed sensor
Open/short or intermittent wiring/conductor to sensor
Corroded/loose connector at the sensor or ABS module
Damaged or missing tone ring teeth or heavy rust/debris
Sensor air gap out of specification due to bearing/wheel issues

Fault status

⚠️ Status

ABS control module detected a wheel speed sensor circuit malfunction — possible open/short, missing or erratic sensor signal. ABS/traction control may be disabled for safety.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2 hours