C0030
Left Front Wheel Speed Sensor Circuit Range/Performance
The signal from the left front wheel speed sensor is implausible relative to the other wheels. Typical causes are excessive air gap, contaminated tone ring or partial sensor failure.
- Check engine light: Not always
- Emissions related: No
- Repair difficulty: medium
Symptoms
- ABS warning light on
- ESC/stability control deactivated
- Possible reduced brake assist
- Speedometer may behave erratically
Common causes
Ordered by how often each turns out to be the cause.
- Metal debris on tone ring (magnetic encoder)Common
- Sensor air gap too largePossible
- Sensor intermittent at temperaturePossible
Parts involved
- Wheel Speed Sensor Fl
- Tone Ring
- Hub Bearing
C0030 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.