P28B5Cylinder 10 Ion Current Sense Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- P28B5 reports an ion signal from cylinder 10 that is electrically valid yet implausible: its amplitude or timing after the spark does not fit the load point or departs from the remaining cylinders. Because ionisation depends on how hot and dense the burning charge is, causes include an eroded electrode gap, oil-wetted plugs, mixture errors on cylinder 10 or a compression loss. Saab's T7 V6 evaluated the ion flow of each bank for knock and retarded the affected cylinder step by step, so an untrustworthy signal tends to show up as erratic timing. No manufacturer publicly documents P28B5, and an ion-sensing V10 or V12 is not described. P28B4, P28B6 and P28B7 are the electrical faults; P0310 may accompany it.
- What you may notice
- MIL, sometimes together with P0310
- Erratic ignition timing on cylinder 10
- Hesitation when accelerating
- Likely causes
- LikelyEroded electrode gap on the cylinder 10 plug
- PossibleOil-wetted plug in cylinder 10
- PossibleMixture error on cylinder 10
- RareCompression loss in cylinder 10
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · 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.