P28C0Ion Sense Module Supply Voltage Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P28C0 points to a fault in the power feed of the module that conditions ion signals – typically an open fuse, relay contact or wire, so the module is not powered at all. On Saab's Trionic T8 that module receives battery voltage via the main relay and its ground from a body point, and on the older T7 the ignition cassette took the same route. Saab's nearest code, P1310 (bank 2: P1320), required a turning crankshaft and more than 6 V at the main relay, then flagged the fault when every trigger output stayed under 2 V for one second. Saab cut fuel in response, on the V6 for every cylinder although just one cassette had failed, yet treated it as Type III without a warning lamp. No manufacturer documents P28C0 itself. P28C1 and P28C2 cover a supply that is present but too low or too high.
- What you may notice
- Engine cranks but does not start, or cuts out while driving
- Ion-based misfire and knock detection lost on all cylinders
- Warning lamp behaviour depends on the manufacturer
- Likely causes
- LikelyBlown fuse in the ion sense module feed
- PossibleMain relay not switching through or burnt contact
- PossibleOpen supply wire or loose ground point of the module
- RareInternal fault in the module's power stage
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €10 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.