Powertrain, generic (extended)

P289B Cylinder 3 Ion Current Sense Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P289B signals that the ion channel of cylinder 3 sits permanently above its upper limit. A conductor touching battery voltage, a coil that couples ignition energy into its measuring output, or a lost ground reference are the usual electrical reasons. Saab shows a comparable bank-level check on the Trionic T7 V6, where cylinder 3 belongs to bank 1 together with 1 and 5: its code P1313 is set when the combustion detection line stays above 5 V for 200 combustions and clears after 300 without fault. On the 2009 four-cylinder module, cylinder 3 has trigger input pin 2 and ion input pin 8, which makes targeted voltage checks easy. No manufacturer publishes P289B. The low-side counterpart is P289A.

Likely causes

Ion signal wire of cylinder 3 shorted to battery or supply voltage
Coil 3 coupling ignition energy into its measuring output
Missing ground reference at coil 3 or the processing module

Symptoms

  • MIL with high ion signal fault on cylinder 3
  • Knock on cylinder 3 may go undetected, so timing is retarded
  • Reduced pulling power

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 3ignition coil cyl 3ion sense module

Related codes

P2898P2899P289AP2897P289F

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