P289FCylinder 4 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
- P289F is set when the ion measurement of cylinder 4 is held above its plausible maximum. Electrically, look for a signal conductor in contact with a supply feed, an internally leaking coil 4, or a poor ground that lifts the reference level. On Saab's T7 V6, cylinder 4 is part of bank 2 with cylinders 2 and 6; there a combustion detection line above 5 V for 200 combustions sets Saab code P1324, which needs 300 fault-free combustions to report OK. On the 2009 four-cylinder module, the ignition trigger of cylinder 4 enters on pin 1, the ion signal on pin 15. A permanently high channel hides the knock oscillations, so timing is retarded. No manufacturer publishes P289F; P289E is the low case.
- What you may notice
- MIL with high ion signal on cylinder 4
- Reduced performance from retarded ignition
- Knock protection on cylinder 4 weakened
- Likely causes
- LikelyIon signal conductor of cylinder 4 touching a supply feed
- PossibleInternal leakage in coil 4 raising the measuring output
- RarePoor ground lifting the reference of the cylinder 4 channel
- 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 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.