C0021moderate severityChassis
LF Wheel Speed Sensor Range/Performance
on 2002 GMC Envoy 4.2L I6 · 4WD
What this code means
The left front wheel speed sensor output is outside the expected range under current driving conditions.
Symptoms
- ABS warning light on
- Traction control light on
- Speedometer fluctuation
- ABS activating at inappropriate times
Common causes
- Wheel speed sensor air gap too large
- Tone ring corrosion or damage
- Sensor magnet weakened
- Wheel bearing excessive play
Diagnostic steps
- Compare all four wheel speed sensor readings at steady speed
- Inspect sensor air gap with feeler gauge
- Check tone ring for missing teeth or rust
- Inspect wheel bearing for play
- Scope sensor output waveform
Repair notes
Adjust sensor air gap or replace sensor. Inspect tone ring for damage.
Other Chassis codes on this vehicle
C0022
RF Wheel Speed Sensor Range/Performance
C0022
RF Wheel Speed Sensor Range/Performance
C0023
LR Wheel Speed Sensor Range/Performance
C0023
LR Wheel Speed Sensor Range/Performance
C0024
RR Wheel Speed Sensor Range/Performance
C0024
RR Wheel Speed Sensor Range/Performance
C0025
LF Wheel Speed Sensor Circuit Intermittent
C0025
LF Wheel Speed Sensor Circuit Intermittent
C0026
RF Wheel Speed Sensor Circuit Intermittent
C0026
RF Wheel Speed Sensor Circuit Intermittent