C0040
System
Chassis (ABS)
Scanner required
Full-system scanner (engine, ABS, SRS, transmission, service resets)

Right Front Wheel Speed Sensor Circuit

Understand C0040, common causes, and the right TOPDON scanner to diagnose it.

Right front wheel speed sensor signal fault — mirror of C0035 on the opposite corner.

Common symptoms

  • ABS light
  • Traction control disabled

Typical causes

  • Failed RF sensor
  • Tone ring damage
  • Brake dust on sensor tip
  • Wiring harness at strut

What scanner do you need?

Full-system scanner (engine, ABS, SRS, transmission, service resets)

Use live data and freeze frame to confirm the fault before replacing parts. ABS, SRS, and network U-codes usually require a full-system scanner.

Diagnostic tips

  • Record freeze frame data when the code first sets
  • Clear the code only after fixing the root cause
  • Check for related pending codes that point to a common issue
  • Verify battery voltage is above 12.4V before chasing sensor codes

Recommended TOPDON scanners

Frequently asked questions

Can I diagnose C0040 with a basic code reader?
C0040 may set in the engine module, but related diagnostics often benefit from an enhanced or full-system scanner with live data and freeze frame.
Is it safe to drive with C0040?
It depends on the code and symptoms. Flashing check engine lights and misfire codes should be addressed immediately. Consult a professional if unsure.