Powertrain, generic (extended)

P289F Cylinder 4 Ion Current Sense Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

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.

Likely causes

Ion signal conductor of cylinder 4 touching a supply feed
Internal leakage in coil 4 raising the measuring output
Poor ground lifting the reference of the cylinder 4 channel

Symptoms

  • MIL with high ion signal on cylinder 4
  • Reduced performance from retarded ignition
  • Knock protection on cylinder 4 weakened

Repair estimate

DifficultyMediumDIY possible
Parts and labour€40–600
Time0.3–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

spark plug cyl 4ignition coil cyl 4ion sense module

Related codes

P289CP289DP289EP289BP2893

References: law.cornell.edu, saabwisonline.com, saabwisonline.com.