OBD-II code · Powertrain (generic, extended)
P28AC Cylinder 8 Ion Current Sense Circuit
The ECM cannot read a valid ion current signal from cylinder 8. Ion current sensing relies on the spark plug acting as an electrode after combustion.
Is it safe to drive with P28AC?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyIon sense module failed
- PossibleWiring or connector fault
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–3 h
- Emissions test
- Likely to fail
- Parts involved
- Spark Plug Cyl 8, Ignition Coil Cyl 8, Ion Sense Module
Related codes
- P2890Cylinder 1 Ion Current Sense Circuit
- P2894Cylinder 2 Ion Current Sense Circuit
- P2898Cylinder 3 Ion Current Sense Circuit
- P289CCylinder 4 Ion Current Sense Circuit
- P28A0Cylinder 5 Ion Current Sense Circuit
- P28A4Cylinder 6 Ion Current Sense Circuit
- P28A8Cylinder 7 Ion Current Sense Circuit
- P28B0Cylinder 9 Ion Current Sense Circuit
- P28B4Cylinder 10 Ion Current Sense Circuit
- P28B8Cylinder 11 Ion Current Sense Circuit
- P28BCCylinder 12 Ion Current Sense Circuit
- P28A9Cylinder 7 Ion Current Sense Circuit Range/Performance
- P28AACylinder 7 Ion Current Sense Circuit Low
- P28ABCylinder 7 Ion Current Sense Circuit High
- P28ADCylinder 8 Ion Current Sense Circuit Range/Performance
- P28AECylinder 8 Ion Current Sense Circuit Low
- P28AFCylinder 8 Ion Current Sense Circuit High
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.