Code
C0662
Generic
C — Chassis
Left Rear Wheel Speed Sensor B Circuit High
Views:
UK: 22
EN: 35
RU: 25
AI status
Completed
Completed
100%
Causes
- Damaged or failed left rear wheel speed sensor (active or passive)
- Short to battery voltage in left rear sensor wiring
- Corroded/loose connector or poor ground at sensor
- Damaged, cracked, missing or contaminated tone ring/reluctor at the left rear wheel
- Intermittent/open/shorted wiring between sensor and ABS/traction control module
- Faulty ABS/traction control module input circuit
Symptoms
- ABS/ESP warning lamp illuminated
- Uneven or disabled ABS operation; traction control may be limited or disabled
- Possible altered vehicle stability or longer braking distances under ABS activation
- Reduced drivability during wheel slip events (traction control interventions)
- Inconsistent or incorrect wheel speed readings in scan tool live data for left rear wheel
What to check
- Scan vehicle for stored ABS/ESP codes and note freeze frame data
- Compare live wheel speed readings for all four wheels at low vehicle speed using a scan tool
- Visually inspect left rear wheel sensor connector, wiring harness, and tone ring for damage, contamination or missing teeth
- Wiggle and flex wiring and connector while monitoring live data for intermittent changes
- Measure sensor connector for proper supply/reference voltage and ground (if an active sensor)
- Measure sensor resistance (for passive sensors) and check for short to battery/ground
Signal parameters
- Passive (variable reluctance) sensor: AC voltage waveform; ~0 V at rest; AC amplitude increases with wheel speed (typical low-speed amplitudes 0.1–2 Vpp, increasing at higher speeds). DC resistance typically in the hundreds to a few kilo-ohms range depending on design.
- Active (Hall/active) sensor: Square/pulse waveform referenced to sensor supply; typically 0–5 V or 0–12 V pulses, frequency proportional to wheel speed; sensor requires proper supply (often 5 V or ignition 12 V) and ground.
- Expected behavior: left rear wheel speed frequency and amplitude should match other wheels proportionally; no voltage or wildly higher/lower amplitude compared with opposite wheel or other corners.
Diagnostic algorithm
- Connect a professional scan tool and record C0662 plus any related codes and freeze frame data; monitor all four wheel speed values while slowly rotating the left rear wheel or performing a low-speed drive-by.
- Perform a visual inspection: remove wheel if needed and inspect sensor, connector, harness, and tone ring for damage, debris, missing teeth, or corrosion.
- With ignition ON (engine off) verify sensor supply/reference and ground at the sensor connector (active sensors). Compare voltages to vehicle manufacturer specs or to another wheel sensor circuit.
- For passive sensors, disconnect sensor and measure resistance across the sensor terminals. Compare to specification or a known-good sensor. Check for short to ground or battery using multimeter.
- Spin the wheel by hand (wheel off the ground, vehicle securely supported on jack stands, parking brake set, and wheel chocked) and measure AC voltage at the sensor or view waveform on an oscilloscope. Look for a clean, regular waveform that increases with speed.
- Wiggle-test the harness and connector while watching live data or oscilloscope for intermittent changes indicating a wiring fault.
- Perform continuity tests between the sensor connector and the ABS module pin(s) to check for opens or high resistance. Also check for short to power/ground.
- If wiring and connector are good but no valid signal, replace the left rear wheel speed sensor and retest.
- If replacement sensor also fails or wiring/mod module tests show faults at module connector, consider ABS module input fault and follow manufacturer procedures for module diagnosis/repair.
- After repairs, clear codes, perform a test drive to verify the code does not return and that wheel speed readings are normal.
Likely causes
- Connector corrosion or bent pins at the left rear sensor
- Chafed or pinched wiring contacting chassis or power circuit
- Damaged tone ring (missing teeth or heavy rust) near left rear wheel
- Failed sensor from contamination or internal short
- Poor sensor ground or reference voltage supply
Fault status
Status
C0662 — Left Rear Wheel Speed Sensor B Circuit High: ABS/traction control module detects a high or abnormally high signal from the left rear wheel speed sensor circuit.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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