Code
C0037
Generic
C — Chassis
Left Rear Wheel Speed Sensor
Views:
UK: 46
EN: 78
RU: 89
AI status
Completed
Completed
100%
Causes
- Damaged or disconnected left rear wheel speed sensor
- Corroded or loose sensor connector or wiring harness
- Broken or missing tone/ring teeth (reluctor) on hub/drive flange
- Short to power or ground in the sensor circuit
- Contaminated sensor (metal shavings, heavy debris) or magnetized build-up
- Faulty ABS/ESC control module or poor ground at module
Symptoms
- ABS, ESC or traction control warning lamp illuminated
- Reduced or no ABS/ESC/TC functionality (system enters limp behavior)
- Possible ABS activation at low speeds or wheel lock during braking
- Inconsistent or no speed reading from left rear on live-data screens
- Noise or vibration if sensor is contacting rotating parts
What to check
- Read stored and pending ABS/ESC codes with scan tool; note freeze-frame data
- View live wheel speed sensor data while rolling vehicle slowly on jack or road test
- Visual inspection of left rear sensor, tone ring, connector and wiring for damage/corrosion
- Measure sensor resistance (passive) or check supply/reference and signal (active) per manufacturer specs
- Wiggle test harness while monitoring live data to find intermittent faults
- Check for continuity and short to ground/power between sensor wires and chassis
Signal parameters
- Passive (magnetic) sensor: AC voltage amplitude increases with wheel speed; open circuit = infinite resistance
- Active (hall/VR with electronics): typically 5 V reference, ground, and pulsed square/sine signal (frequency proportional to speed)
- Typical resistance ranges: passive sensor commonly 800–2000 ohms (varies by vehicle) — consult spec
- Signal frequency/duty cycle increases with wheel RPM; amplitude and shape depend on sensor type
- No signal, constant voltage, or implausible values indicate open/short/faulty sensor or damaged tone ring
Diagnostic algorithm
- Confirm C0037 and any related codes with a scan tool. Clear codes and road test to verify reappearance.
- Inspect sensor and harness at left rear for physical damage, contamination, connector corrosion, bent pins, or loose mounting.
- With vehicle safely supported and wheel free to rotate, monitor left rear wheel speed signal on a scope or scan tool while rotating wheel by hand or driving slowly. Compare to other wheels.
- Measure sensor resistance (for passive sensors). Replace if open or out of specification. For active sensors, check 5 V reference and ground at connector, then check signal while rotating.
- Perform wiggle/strain test on wiring from wheel to chassis while watching live data for intermittent changes. Repair any chafed or broken wires.
- Inspect tone ring/reluctor for missing/bent teeth, heavy corrosion, or contact with sensor. Repair or replace damaged tone ring or hub.
- Check for short to battery or ground between sensor signal and other wires; repair short circuits.
- If sensor and wiring OK, test ABS module inputs or replace control module only after verifying upstream components and grounds.
- After repairs, clear codes and perform road test and final verification of wheel speed signals and system operation.
Likely causes
- Wiring harness damaged at suspension joint or wheel (constant flex area)
- Corroded/loose connector at the wheel or ABS module
- Failed passive sensor (open or high resistance) or active sensor electronics
- Physical damage to tone ring (missing teeth, heavy corrosion) reducing signal amplitude
Fault status
Status
Left Rear Wheel Speed Sensor Circuit — signal missing, implausible, open or short detected.
Repair difficulty: Medium
Diagnostic time: 0.5 - 2.0 hours
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