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Home / DTC / C1045 — Left rear wheel speed sensor

C1045 — Left rear wheel speed sensor

Detailed page for trouble code C1045.

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Code

C1045

ALFA ROMEO C — Chassis

Left rear wheel speed sensor

Brand: ALFA ROMEO
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or contaminated left rear wheel speed sensor
  • Broken, shorted or corroded wiring/connector between sensor and ABS control module
  • Damaged or missing tone ring/reluctor on the left rear hub
  • Air gap too large (sensor-to-ring distance) or misalignment
  • Faulty ABS/traction control module or internal connector fault
  • Intermittent ground or power supply fault to the sensor

Symptoms

  • ABS warning lamp and/or traction control (ESP) light illuminated
  • Stability/traction control functions disabled or reduced
  • ABS may activate incorrectly or not function under braking
  • Possible speedometer or cruise control faults on some models
  • Inconsistent or jittery brake feel under hard braking

What to check

  • Retrieve freeze-frame and live data with a diagnostic scanner; observe left rear wheel speed value versus other wheels
  • Visually inspect the left rear sensor, connector and tone ring for damage, contamination or missing teeth
  • Check connector for corrosion, bent pins, water intrusion and proper locking
  • Measure sensor supply, ground and signal at the harness connector with key ON (if active sensor)
  • Measure sensor coil resistance (for passive/VR sensors) and compare to spec
  • Back-probe the sensor while rotating the wheel and observe signal with a multimeter or oscilloscope

Signal parameters

  • Passive (VR) sensor: AC voltage proportional to speed; typical coil resistance commonly ~500–2000 Ω (model dependent)
  • Active (Hall/3‑wire) sensor: digital square wave referenced to vehicle supply (commonly ~5V or 12V) — check for pull‑up voltage
  • At low speeds VR sensors produce small AC voltages (tens to hundreds mV); amplitude rises with speed
  • Oscilloscope waveform should be clean sinusoidal (VR) or square pulse (Hall) with consistent frequency matching wheel speed

Diagnostic algorithm

  1. Connect scanner, confirm C1045 and note any other ABS/traction codes and freeze-frame data.
  2. Visually inspect the left rear sensor, harness routing, clips and tone ring. Repair obvious damage or contamination.
  3. Disconnect sensor connector, check for corrosion, bent pins and secure mating. Clean and apply dielectric grease if appropriate.
  4. Measure sensor resistance (for passive) or supply/pulse (for active) at the connector. Compare to factory spec.
  5. With wheel elevated, back-probe signal wire and spin the wheel. Use a scope or meter to confirm presence and quality of waveform.
  6. If no/poor signal at sensor connector but good signal at ABS module connector, inspect/repair wiring between them (continuity, short to ground/power).
  7. If wiring and connector are good but no proper signal, replace the left rear wheel speed sensor and retest.
  8. If new sensor still fails and wiring checks good, suspect ABS control module fault or internal connector issue; consult module-level diagnostics/service manual.
  9. Clear codes and perform a road test to confirm fault does not return.

Likely causes

  • Corroded connector at the left rear sensor
  • Sensor ruined by road debris, hub servicing or brake work
  • Tone ring cracked, missing teeth, or covered in rust/metal shavings
  • Wire rubbed through at suspension pivot or inside trunk wheelwell
  • Moisture ingress into sensor or connector causing intermittent failure

Fault status

⚠️ Status
Left rear wheel speed sensor malfunction detected — signal missing or out of expected range
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

C1040 C1035 C1030 C1085 C1000
89

Browse 89 ALFA ROMEO manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

ALFA ROMEO

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Code

C1045

FIAT C — Chassis

Left rear wheel speed sensor

Brand: FIAT
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or contaminated left rear wheel speed sensor
  • Broken, shorted or corroded wiring/connector between sensor and ABS control module
  • Damaged or missing tone ring/reluctor on the left rear hub
  • Air gap too large (sensor-to-ring distance) or misalignment
  • Faulty ABS/traction control module or internal connector fault
  • Intermittent ground or power supply fault to the sensor

Symptoms

  • ABS warning lamp and/or traction control (ESP) light illuminated
  • Stability/traction control functions disabled or reduced
  • ABS may activate incorrectly or not function under braking
  • Possible speedometer or cruise control faults on some models
  • Inconsistent or jittery brake feel under hard braking

What to check

  • Retrieve freeze-frame and live data with a diagnostic scanner; observe left rear wheel speed value versus other wheels
  • Visually inspect the left rear sensor, connector and tone ring for damage, contamination or missing teeth
  • Check connector for corrosion, bent pins, water intrusion and proper locking
  • Measure sensor supply, ground and signal at the harness connector with key ON (if active sensor)
  • Measure sensor coil resistance (for passive/VR sensors) and compare to spec
  • Back-probe the sensor while rotating the wheel and observe signal with a multimeter or oscilloscope

Signal parameters

  • Passive (VR) sensor: AC voltage proportional to speed; typical coil resistance commonly ~500–2000 Ω (model dependent)
  • Active (Hall/3‑wire) sensor: digital square wave referenced to vehicle supply (commonly ~5V or 12V) — check for pull‑up voltage
  • At low speeds VR sensors produce small AC voltages (tens to hundreds mV); amplitude rises with speed
  • Oscilloscope waveform should be clean sinusoidal (VR) or square pulse (Hall) with consistent frequency matching wheel speed

Diagnostic algorithm

  1. Connect scanner, confirm C1045 and note any other ABS/traction codes and freeze-frame data.
  2. Visually inspect the left rear sensor, harness routing, clips and tone ring. Repair obvious damage or contamination.
  3. Disconnect sensor connector, check for corrosion, bent pins and secure mating. Clean and apply dielectric grease if appropriate.
  4. Measure sensor resistance (for passive) or supply/pulse (for active) at the connector. Compare to factory spec.
  5. With wheel elevated, back-probe signal wire and spin the wheel. Use a scope or meter to confirm presence and quality of waveform.
  6. If no/poor signal at sensor connector but good signal at ABS module connector, inspect/repair wiring between them (continuity, short to ground/power).
  7. If wiring and connector are good but no proper signal, replace the left rear wheel speed sensor and retest.
  8. If new sensor still fails and wiring checks good, suspect ABS control module fault or internal connector issue; consult module-level diagnostics/service manual.
  9. Clear codes and perform a road test to confirm fault does not return.

Likely causes

  • Corroded connector at the left rear sensor
  • Sensor ruined by road debris, hub servicing or brake work
  • Tone ring cracked, missing teeth, or covered in rust/metal shavings
  • Wire rubbed through at suspension pivot or inside trunk wheelwell
  • Moisture ingress into sensor or connector causing intermittent failure

Fault status

⚠️ Status
Left rear wheel speed sensor malfunction detected — signal missing or out of expected range
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

C1040 C1035 C1030 C1085 C1000
Repair manuals

Manual library for FIAT

26

Browse 26 FIAT manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

FIAT

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Code

C1045

LAND ROVER C — Chassis

Hydraulic residual pressure

Brand: LAND ROVER
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or contaminated left rear wheel speed sensor
  • Broken, shorted or corroded wiring/connector between sensor and ABS control module
  • Damaged or missing tone ring/reluctor on the left rear hub
  • Air gap too large (sensor-to-ring distance) or misalignment
  • Faulty ABS/traction control module or internal connector fault
  • Intermittent ground or power supply fault to the sensor

Symptoms

  • ABS warning lamp and/or traction control (ESP) light illuminated
  • Stability/traction control functions disabled or reduced
  • ABS may activate incorrectly or not function under braking
  • Possible speedometer or cruise control faults on some models
  • Inconsistent or jittery brake feel under hard braking

What to check

  • Retrieve freeze-frame and live data with a diagnostic scanner; observe left rear wheel speed value versus other wheels
  • Visually inspect the left rear sensor, connector and tone ring for damage, contamination or missing teeth
  • Check connector for corrosion, bent pins, water intrusion and proper locking
  • Measure sensor supply, ground and signal at the harness connector with key ON (if active sensor)
  • Measure sensor coil resistance (for passive/VR sensors) and compare to spec
  • Back-probe the sensor while rotating the wheel and observe signal with a multimeter or oscilloscope

Signal parameters

  • Passive (VR) sensor: AC voltage proportional to speed; typical coil resistance commonly ~500–2000 Ω (model dependent)
  • Active (Hall/3‑wire) sensor: digital square wave referenced to vehicle supply (commonly ~5V or 12V) — check for pull‑up voltage
  • At low speeds VR sensors produce small AC voltages (tens to hundreds mV); amplitude rises with speed
  • Oscilloscope waveform should be clean sinusoidal (VR) or square pulse (Hall) with consistent frequency matching wheel speed

Diagnostic algorithm

  1. Connect scanner, confirm C1045 and note any other ABS/traction codes and freeze-frame data.
  2. Visually inspect the left rear sensor, harness routing, clips and tone ring. Repair obvious damage or contamination.
  3. Disconnect sensor connector, check for corrosion, bent pins and secure mating. Clean and apply dielectric grease if appropriate.
  4. Measure sensor resistance (for passive) or supply/pulse (for active) at the connector. Compare to factory spec.
  5. With wheel elevated, back-probe signal wire and spin the wheel. Use a scope or meter to confirm presence and quality of waveform.
  6. If no/poor signal at sensor connector but good signal at ABS module connector, inspect/repair wiring between them (continuity, short to ground/power).
  7. If wiring and connector are good but no proper signal, replace the left rear wheel speed sensor and retest.
  8. If new sensor still fails and wiring checks good, suspect ABS control module fault or internal connector issue; consult module-level diagnostics/service manual.
  9. Clear codes and perform a road test to confirm fault does not return.

Likely causes

  • Corroded connector at the left rear sensor
  • Sensor ruined by road debris, hub servicing or brake work
  • Tone ring cracked, missing teeth, or covered in rust/metal shavings
  • Wire rubbed through at suspension pivot or inside trunk wheelwell
  • Moisture ingress into sensor or connector causing intermittent failure

Fault status

⚠️ Status
Left rear wheel speed sensor malfunction detected — signal missing or out of expected range
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

C1040 C1035 C1030 C1085 C1000
267

Browse 267 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

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