P28B6 code meaning
Cylinder 10 Ion Current Sense Circuit Low
Powertrain system Generic code P28xx codes Check engine light
What P28B6 means
P28B6 is set when the cylinder 10 ion reading is persistently too low. The measuring bias that should sit across the gap between sparks is missing or being drained: a coil 10 whose bias generator has failed, conductive deposits bridging the plug insulator, a wet trunk, or a sense wire with insulation damage touching ground. Saab's T7 applied 80 V for this purpose, the later T8 about 120 V; either way, a short to ground collapses it. The engine computer then lacks combustion confirmation for cylinder 10, may log P0310 and usually falls back to cautious timing. No manufacturer documents P28B6 publicly, and no ion-sensing engine with ten or more cylinders is known. The high-side code is P28B7.
P28B6 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 P28B6
- MIL with low ion reading on cylinder 10
- P0310 may be stored as well
- Cautious ignition timing, less pulling power
Common causes of P28B6
- Most likelyConductive deposits bridging the cylinder 10 plug insulator
- PossibleCylinder 10 sense wire with damaged insulation touching ground
- PossibleBias generator of coil 10 failed
- Less likelyWet plug trunk on cylinder 10
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Spark plug cyl 10Ignition coil cyl 10Ion sense module
What each part of P28B6 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. |
| B6 | The exact fault in that area. |
What to do next
- Note P28B6 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 P28B6
What does P28B6 mean?
P28B6 means "Cylinder 10 Ion Current Sense Circuit Low". P28B6 is set when the cylinder 10 ion reading is persistently too low. It is a generic code, so it means the same on every make.
Is it safe to drive with P28B6?
Drive gently and only to a workshop. With P28B6 the car can go into limp mode (reduced power) to protect itself.
Will P28B6 fail an emissions test?
Yes, it can. P28B6 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 P28B6 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 P28B6 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.