P28C0
Ion Sense Module Supply Voltage Circuit
The ECM detects a generic fault on the supply voltage circuit of the ion sense module. The module can no longer reliably bias the spark plug for ion current measurement.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Module supply rail interruptedCommon
- Wiring or connector faultPossible
Parts involved
- Ion Sense Module
- Wiring Harness
P28C0 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.