P28C0 code meaning
Ion Sense Module Supply Voltage Circuit
Powertrain system Generic code P28xx codes Check engine light
What P28C0 means
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.
P28C0 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P28C0
- 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
Common causes of P28C0
- Most 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
- Less likelyInternal fault in the module's power stage
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Ion sense moduleWiring harness
What each part of P28C0 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| 8 | Area: transmission. |
| C0 | The exact fault in that area. |
What to do next
- Note P28C0 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P28C0
What does P28C0 mean?
P28C0 means "Ion Sense Module Supply Voltage Circuit". 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. It is a generic code, so it means the same on every make.
Is it safe to drive with P28C0?
Drive gently and only to a workshop. With P28C0 the car can go into limp mode (reduced power) to protect itself.
Will P28C0 fail an emissions test?
Yes, it can. P28C0 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P28C0 to fix?
Difficulty: medium. A typical repair takes 0.3 to 2.5 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P28C0 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.