C1143

Code

Other C — Chassis

Wheel Speed Sensor LR Tone Ring Tooth Missing Fault

Brand: Other

Type: C — Chassis

Views: UK: 38 EN: 58 RU: 65

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Physical damage or missing tone ring tooth(s) on LR wheel hub/tone ring assembly
Contaminated, cracked, bent, or magnetized tone ring
Loose, damaged, corroded, or disconnected LR wheel speed sensor or connector
Incorrect sensor air gap or misaligned sensor
Damaged wiring, short or open circuit, or intermittent connector contact
Faulty wheel speed sensor (active or passive)

Symptoms

ABS, ESC or traction control warning lamp illuminated
Intermittent or constant ABS/ESC fault stored for LR wheel speed
Unexpected ABS activation or pulsing under light braking
Traction control or stability control may be disabled or behave erratically
Speedometer or vehicle speed reading irregular (in some vehicles)

What to check

Read full ABS/ESC module codes and freeze frame with a scan tool
Visually inspect LR tone ring for missing/broken teeth, cracks, corrosion or heavy contamination
Inspect LR wheel speed sensor for damage, mounting position, and presence of debris
Check sensor connector for corrosion, pushed-out pins, and secure locking
Wiggle harness and connectors while monitoring live wheel speed data to find intermittent faults
Compare LR wheel speed raw data to other wheels at low speed using scan tool/live data

Signal parameters

Passive (variable-reluctance) sensor: produces AC sine/peaks that increase with speed; amplitude typically 0.1–5 V peak depending on speed and sensor design (varies by vehicle)
Active (Hall/electronic) sensor: produces digital square wave or switched output; typical logic levels 0–5 V (or 0–12 V on some systems) and frequency proportional to wheel speed
Expected pulses: consistent regular spacing corresponding to tone ring tooth count at given wheel rotational speed; a missing tooth shows as a skipped pulse or irregular spacing
Typical sensor resistance (passive/VR): commonly in the hundreds to low thousands of ohms — consult vehicle spec for exact value

Diagnostic algorithm

Safety first: secure vehicle on level surface, with parking brake applied and wheels chocked. Use jack stands if wheel must be removed.
Use scan tool: read codes, freeze frame, live data. Confirm code C1143 and note whether code is active or historic. Clear codes and perform a low-speed road test while monitoring LR wheel speed signal to reproduce.
Visual inspection: remove wheel (if necessary). Inspect LR tone ring for missing or damaged teeth, build-up of debris, cracks, or bending. Inspect hub/bearing area for play or damage.
Inspect sensor: check sensor face for contamination or damage. Verify sensor mounting bolt is tight and sensor is positioned correctly with correct air gap per spec.
Electrical checks: disconnect sensor and measure resistance across sensor terminals; check for open/short to chassis ground and to ABS module connector. Backprobe connector and wiggle harness while watching live data for dropouts.
Waveform check: spin wheel by hand or road test with oscilloscope and compare LR waveform to opposite wheel. Look for missing pulses, irregular amplitude, or noise.
If wiring or connector faults found, repair or replace as needed and re-test. If waveform is absent or weak with good wiring, replace sensor.
If tone ring is damaged or missing tooth(s), replace tone ring or hub assembly (may require bearing/hub replacement if integrated). Reassemble, clear codes and road test to confirm fault cleared.
If intermittent and no mechanical fault found, inspect ABS module grounds and wiring harness routing; consider module or sensor harness replacement if fault persists.
Note: when tone ring is integral to hub bearing the repair can require hub/bearing replacement. Always follow manufacturer torque and installation procedures.

Likely causes

Mechanical damage to LR tone ring (missing tooth, cracked, corrosion)
Sensor mounting bolt loose or sensor pushed away causing excessive gap
Contaminated sensor face (metal shavings, brake dust) or embedded debris in tone ring
Broken/shorted wiring or rubbed-through insulation near suspension or hub
Failed LR wheel speed sensor internally (open/short or weak output)

Fault status

⚠️ Status

Stored when the ABS/ESC controller detects a missing or irregular pulse from the left-rear wheel speed sensor consistent with a missing or damaged tone ring tooth. May be active or stored as a history code; usually accompanied by ABS/traction control warning lamp.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours