P28A7Cylinder 6 Ion Current Sense Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P28A7 is logged when the ion signal of cylinder 6 is held above the upper limit the module accepts. A conductor in contact with battery voltage, crosstalk from the primary side of coil 6, or an evaluation stage driven into saturation are the typical electrical explanations. Saab's T7 V6 handled the comparable fault per bank: cylinder 6 belongs to bank 2, whose combustion line triggers Saab code P1324 when it stays above 5 V for 200 combustions; the knock information of that bank travels separately to engine module pin 62. A saturated channel leaves no room for the knock oscillations, so the module retards timing on cylinder 6. No manufacturer documents P28A7 publicly. The low-side counterpart is P28A6.
- What you may notice
- MIL with high ion signal on cylinder 6
- Less power because of late ignition on cylinder 6
- Knock on cylinder 6 may not be detected
- Likely causes
- LikelyIon conductor of cylinder 6 touching battery voltage
- PossibleCrosstalk from the primary side of coil 6
- RareEvaluation stage for cylinder 6 saturated
- 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: €40 – €650
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.