ABS and brakes

C0045 — Right Rear Wheel Speed Sensor Circuit Range/Performance

Severity: medium Drive with care, to a shop

What C0045 means

The ABS module constantly compares the speed signals from all four wheels. C0045 is set when the right rear sensor signal is out of range or does not match the other wheels. The sensor normally reads pulses from a toothed tone ring on the hub, and without a clean signal the system cannot track wheel rotation. Some references mention the left side, but the code name points to the right rear, so confirm the location with a scan tool.

Symptoms

  • ABS warning light on
  • Traction/stability control lights on
  • ABS and stability control not working
  • Wheels lock up easily under hard braking
  • Occasional false ABS activation
  • Erratic speedometer on some models

Possible causes

  1. Failed right rear wheel speed sensor
  2. Damaged or corroded wiring or connector at the sensor
  3. Dirty, cracked or damaged tone (reluctor) ring
  4. Worn wheel bearing causing excess play or air gap
  5. Sensor clogged with metal debris or installed incorrectly
  6. ABS module fault or communication problem (less common)

How to diagnose

  1. Scan for codes with an ABS-capable tool and compare live wheel speed data on a test drive.
  2. Inspect the sensor wiring in the wheel well for chafing, breaks and corrosion.
  3. Check the sensor connector for moisture, corrosion and a secure lock.
  4. Remove the sensor, clean off debris and inspect its tip.
  5. Inspect the tone ring for cracks, missing teeth and rust.
  6. Check wheel bearing play and the sensor air gap.
  7. Test sensor resistance and the circuit for opens and shorts to ground using the manufacturer's specs.
  8. Clear the code and road test to confirm it does not return.

Common fixes

  • Replace the right rear wheel speed sensor
  • Repair the wiring or replace a damaged connector
  • Clean or replace the tone ring, or the hub assembly if it is built in
  • Replace a worn wheel bearing
  • Repair or replace the ABS module if everything else checks out

Questions and answers

Can I drive with code C0045?

Yes, but carefully and not far. The regular brakes work, but ABS and stability control are off, so leave extra distance on wet or slippery roads.

What most often causes C0045?

Usually the sensor itself, its wiring or connector, or a dirty or damaged tone ring. The ABS module is rarely the cause.

Will the code go away on its own?

The light may go out if the fault was a one-off, such as moisture in the connector. The underlying problem usually remains and the code tends to return, so it is best to inspect it soon.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.