C1A3F

Code

Generic C — Chassis

Right rear wheel speed sensor circuit intermittent (ABS module)

Brand: Generic

Type: C — Chassis

Views: UK: 11 EN: 17 RU: 10

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or chafed wiring in the right rear wheel sensor harness
Corroded or loose connector contacts at the sensor or ABS module
Faulty right rear wheel speed sensor (intermittent internal failure)
Contaminated, cracked or missing tone/r reluctor ring teeth
Debris, metal shavings or magnetic material on the sensor/reluctor
Poor ground or reference voltage to the sensor

Symptoms

ABS warning lamp illuminated (may be steady or intermittent)
Traction/stability control warning or reduced functionality
ABS system disabled or ABS activation at inappropriate times
Inconsistent or missing wheel speed reading for right rear on scan tool
Possible intermittent speedometer/driveability effects on some vehicles

What to check

Read ABS/vehicle scan tool codes and freeze frame data; note occurrence conditions
View live wheel speed data for all wheels while spinning the right rear wheel
Visually inspect sensor, connector and wiring for damage, corrosion, loose pins
Wiggle test wiring and connector while observing live data for intermittent changes
Inspect tone/reluctor ring for missing teeth, heavy rust or metal debris
Check sensor mounting gap and alignment to reluctor per OEM spec

Signal parameters

Active (Hall/3-wire) sensors: provide a reference voltage, ground and a digital pulse output; pulses typically switch between low and reference (often 0–5V) as the wheel turns
Passive (2-wire) sensors: generate an AC/sine waveform whose amplitude and frequency increase with wheel speed; waveform should be clean and continuous
Intermittent faults often appear as missing pulses, irregular amplitude, or noisy/distorted waveform when observed with an oscilloscope
Consult the vehicle OEM service data for exact resistance, supply voltage and clearance specifications before replacement or adjustment

Diagnostic algorithm

Verify and record the code(s) and freeze frame data with an OEM-level scan tool. Note whether fault is continuous or intermittent.
Check for related codes (other wheel sensors, power/ground faults, CAN/communication faults) that could affect diagnosis.
Visually inspect the right rear sensor, connector and harness along the entire routing path for chafing, breaks, corrosion, or water ingress.
Disconnect the sensor connector and inspect contacts; clean corrosion and re-seat firmly. Repair or replace damaged connector/pins as needed.
With connector attached, use a scan tool to monitor right rear wheel speed while a technician slowly rotates the wheel (or road test at low speed). Look for dropouts or irregular signals.
Wiggle the wiring harness and connector while monitoring live data to reproduce the intermittent condition. If fault appears, isolate to wiring/harness and repair.
Measure sensor resistance (for passive types) and compare to OEM spec. If out of range or open/shorted, replace the sensor.
Backprobe the sensor connector to verify reference voltage and ground (for active sensors). Check signal with a multimeter and preferably an oscilloscope to view waveform quality.
Inspect reluctor/tone ring for missing or damaged teeth, heavy corrosion or magnetic debris. Clean or replace as required.
If wiring, connector and sensor check good but intermittent continues, test the ABS module input by checking voltage at module connector or consult module bench test/diagnosis procedures; consider module fault only after eliminating external causes.
After repairs, clear codes, perform a road test to verify the issue is resolved and that the ABS/traction warnings do not return.

Likely causes

Connector corrosion or loose pin at sensor or harness splice
Wiring harness damage near suspension/axle where it flexes
Sensor failure due to heat, moisture or impact
Debris buildup on sensor or damaged reluctor ring

Fault status

⚠️ Status

ABS module reports intermittent signal from right rear wheel speed sensor circuit. This may disable ABS/traction control and illuminate warning indicators until the intermittent condition is resolved.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours