P2303
Ignition Coil B Primary Control Circuit Low
The ECU reads a low primary control voltage on ignition coil B. Misfire is typically observed on the cylinder this coil serves.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
Common causes
Ordered by how often each turns out to be the cause.
- Internal coil shortCommon
- Primary wire shorted to groundPossible
- Connector pins corroded - high contact resistanceLess likely
Parts involved
- Ignition Coil
- Coil Driver
- Ignition Wiring
P2303 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.