P28B6Cylinder 10 Ion Current Sense Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- 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 boot, 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.
- What you may notice
- MIL with low ion reading on cylinder 10
- P0310 may be stored as well
- Cautious ignition timing, less pulling power
- Likely causes
- LikelyConductive deposits bridging the cylinder 10 plug insulator
- PossibleCylinder 10 sense wire with damaged insulation touching ground
- PossibleBias generator of coil 10 failed
- RareWet plug boot on cylinder 10
- 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: €30 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.