C0033
Left Front Wheel Speed Sensor Signal Erratic
The control module sees erratic pulses from the left front wheel speed sensor at speed. Common cause is metallic debris on a magnetic encoder or a damaged tone ring.
- 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.
- Magnetic encoder ring contaminatedCommon
- Tone ring cracked or missing teethPossible
- Connector with intermittent contact under vibrationLess likely
Parts involved
- Wheel Speed Sensor Fl
- Tone Ring
- Hub Bearing
C0033 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.