P28C2
Ion Sense Module Supply Voltage High
Supply voltage on the ion sense module is above the expected window. Charging system overvoltage or upstream regulator fault.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Alternator regulator drift - overvoltageCommon
- Supply wire shorted to B+Possible
Parts involved
- Ion Sense Module
- Wiring Harness
P28C2 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.