Code
C2140
Generic
C — Chassis
Rear Right Wheel Speed Sensor Circuit Malfunction
Views:
UK: 4
EN: 5
RU: 5
AI status
Completed
Completed
100%
Causes
- Failed (open/shorted) rear-right wheel speed sensor
- Damaged, corroded or disconnected wiring/connector to the sensor
- Broken/missing or heavily contaminated tone ring (reluctor) or magnetic target
- Faulty ABS/traction control module input or module internal failure
- Poor sensor reference power or ground
- Bad wheel bearing causing sensor misalignment or damage
Symptoms
- ABS, traction control or stability control warning lamp illuminated
- Reduced or disabled ABS/traction control functionality
- Erratic speedometer readings on some vehicles (if driven by wheel sensors)
- ABS modulation or brake feel change during hard braking
- Possible diagnostic trouble codes for other wheel speed sensors or communication faults
What to check
- Read freeze frame and all ABS/traction control codes with a scan tool and note current/previous status
- Visually inspect the RR sensor, connector, wiring harness and tone ring for damage, contamination or missing teeth
- Check for corrosion, bent pins or water entry at the sensor connector
- Backprobe connector and measure sensor resistance and/or AC output while spinning the wheel
- Verify reference power (if 3-wire Hall sensor) and good ground at the sensor connector
- Wiggle wiring harness front-to-back while watching live data for intermittent changes
Signal parameters
- Passive (2-wire) inductive sensor: produces AC voltage proportional to wheel speed; ~0.1–12 V AC depending on speed; frequency increases with wheel rotation
- Active (3-wire Hall-effect/VR) sensor: typically has 5 V reference, ground, and signal output; signal is a square wave 0–5 V (or 0–12 V in some systems) with frequency proportional to speed
- Typical DC resistance for passive sensors: commonly in the hundreds to low thousands of ohms (vehicle-specific) — check OEM spec
- Expected behavior: at rest ~0 V/no signal; when wheel spins steadily, a clean alternating (inductive) or square (active) waveform with frequency increasing with speed; no intermittent dropouts
Diagnostic algorithm
- Retrieve and record all ABS/traction codes and freeze frame data with a scan tool.
- Perform a visual inspection of RR wheel, hub area, sensor, tone ring and harness for damage, contamination or missing reluctor teeth.
- Disconnect sensor connector; check pins for corrosion, bent pins or water ingress; clean and reseal if needed.
- Measure sensor resistance (if applicable) against manufacturer spec. An open reading indicates a broken sensor; a short to ground indicates internal short.
- With connector reconnected, backprobe the signal wire and spin the wheel by hand (or lift vehicle and rotate tire). For passive sensors measure AC voltage; for active sensors check reference voltage (usually ~5 V) and signal waveform with a multimeter or oscilloscope.
- Wiggle the harness and connector while watching live data for dropouts or erratic values to locate intermittent wiring faults.
- If no sensor output and wiring is intact, check continuity between sensor connector and ABS module pin for opens/shorts and verify module power and ground circuits.
- Inspect the tone ring for missing teeth, heavy rust, or metal debris; repair or replace if damaged.
- If wiring and tone ring are good but sensor still fails tests, replace the wheel speed sensor and retest.
- After repair, clear codes and perform a road test or wheel spin test with the scan tool to confirm proper wheel speed readings and that the C2140 does not return.
Likely causes
- Corroded/loose connector at the wheel speed sensor
- Open or short in harness between sensor and ABS module (pin corrosion, chafing)
- Physical damage to tone ring (missing teeth) or heavy contamination (metal shavings, rust)
- Failed wheel speed sensor element (Hall or passive sensor)
- Intermittent module input due to poor ground or supply voltage
Fault status
Status
Rear Right Wheel Speed Sensor Circuit malfunction detected — ABS/traction control may be disabled until the issue is fixed.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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