P28B0 code meaning
Cylinder 9 Ion Current Sense Circuit
Powertrain system Generic code P28xx codes Check engine light
What P28B0 means
P28B0 marks an electrical circuit fault, usually an interruption, in the ion current measurement of cylinder 9. A ninth cylinder appears only on engines with ten or more cylinders, such as V10, V12 or W12 designs. Ion sensing as a production technique is publicly associated with Saab and Mecel, who brought it into series cars with the Trionic systems on four- and six-cylinder engines; for engines of ten or more cylinders no public application exists, and no manufacturer documents P28B0. The working principle would be unchanged: a small voltage across the idle plug gap, a current only when the hot gas ionises, and an evaluation channel per coil. Without that channel cylinder 9 loses misfire and knock evaluation; checks start at coil 9 and its connector.
P28B0 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium, DIY possible
- Typical labor0.3 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P28B0
- MIL with ion circuit fault for cylinder 9
- Misfire and knock evaluation of cylinder 9 suspended
- Slight loss of power from retarded timing
Common causes of P28B0
- Most likelyCoil 9 connector not latched or with spread terminals
- PossibleIon output of coil 9 without function
- PossibleInterrupted ion line of cylinder 9 in the harness
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Spark plug cyl 9Ignition coil cyl 9Ion sense module
What each part of P28B0 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. |
| B0 | The exact fault in that area. |
What to do next
- Note P28B0 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 P28B0
What does P28B0 mean?
P28B0 means "Cylinder 9 Ion Current Sense Circuit". P28B0 marks an electrical circuit fault, usually an interruption, in the ion current measurement of cylinder 9. It is a generic code, so it means the same on every make.
Is it safe to drive with P28B0?
Drive gently and only to a workshop. With P28B0 the car can go into limp mode (reduced power) to protect itself.
Will P28B0 fail an emissions test?
Yes, it can. P28B0 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 P28B0 to fix?
Difficulty: medium. A typical repair takes 0.3 to 3 hours of work. A careful DIY repair is possible with basic tools and a scanner.
Will P28B0 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.