P2C28 code meaning
Fuel Injector Group B Supply Sense Circuit High
Powertrain system Generic code P2Cxx codes Check engine light
What P2C28 means
P2C28 is set when the sense line of the injector group B supply shows more voltage than allowed – either above the upper limit while the group is switched on, or voltage present while the module has switched the group off. Common reasons are a welded injector relay, a supply wire chafed against another powered circuit, or a sense wire shorted to battery voltage. A supply that cannot be switched off matters because the module can no longer isolate the group when it needs to protect an injector or the catalyst. No publicly accessible manufacturer document covers P2C28; it follows CARB's demand for separate high-range codes, and GM's handling of injector supply faults on the Saab 9-5 2.0T (wrong voltage for over 1 s, Type B, injector disabled) gives a comparable logic.
P2C28 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.3 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2C28
- Check engine light
- Often no noticeable change in running
- Battery drain if the relay stays closed after switch-off
Common causes of P2C28
- Most likelyInjector relay contacts stuck closed
- PossibleSense or supply wire shorted to battery voltage
- Less likelyExcessive system voltage from the charging system
- Less likelyInternal fault of the supply switch in the engine control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injector group bWiring harnessECM
What each part of P2C28 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| C | Area: hybrid propulsion. |
| 28 | The exact fault in that area. |
What to do next
- Note P2C28 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 P2C28
What does P2C28 mean?
P2C28 means "Fuel Injector Group B Supply Sense Circuit High". P2C28 is set when the sense line of the injector group B supply shows more voltage than allowed – either above the upper limit while the group is switched on, or voltage present while the module has switched the group off. It is a generic code, so it means the same on every make.
Is it safe to drive with P2C28?
Usually yes, for a short time, if the check engine light is steady and the car drives normally. If the light flashes or the car runs badly, stop and have it checked.
Will P2C28 fail an emissions test?
Yes, it can. P2C28 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 P2C28 to fix?
Difficulty: medium. A typical repair takes 0.3 to 3 hours of work. This is a job for a workshop.
Will P2C28 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.