C2140

Code

Generic C — Chassis

Rear Right Wheel Speed Sensor Circuit Malfunction

Brand: Generic

Type: C — Chassis

Views: UK: 11 EN: 21 RU: 15

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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

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

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

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.

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