P0503
Vehicle Speed Sensor A Circuit Intermittent Erratic or High
Same as P0502 with the signal noisy, erratic or above the plausible upper limit - typical for a chafed harness, missing reluctor tooth or a sensor with a weakened magnet.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: easy
Common causes
Ordered by how often each turns out to be the cause.
- Noise on signal line or intermittent openCommon
- Reluctor ring damaged or missing teethPossible
- Connector with intermittent contact under vibrationLess likely
Parts involved
- Vehicle Speed Sensor A
- VSS Wiring
- Reluctor Ring
P0503 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.