Powertrain, generic (extended)

P2892 Cylinder 1 Ion Current Sense Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2892 says the ion measurement of cylinder 1 delivers a signal that stays below the expected range. Electrically this points to a signal line shorted to ground or a measuring stage that no longer builds up its bias voltage; Saab, for example, applies around 120 V across the plug gap between sparks to obtain the current. A heavily fouled plug can also drag the level down by bleeding off the measuring voltage. When the reading is stuck low, the module can no longer judge combustion in cylinder 1 and typically falls back to a safe ignition map. No manufacturer has published this code; on Saab Trionic T8 engines the cylinder 1 ion line runs from coil pin 4 to the processing module. The high-side fault is P2893, the cylinder 2 equivalent P2896.

Likely causes

Ion signal wire of cylinder 1 shorted to ground
Coil 1 no longer generates its measuring voltage
Spark plug of cylinder 1 with leakage path through deposits

Symptoms

  • MIL and stored fault for cylinder 1
  • Noticeably less power from retarded ignition
  • Possibly unreported misfires on cylinder 1

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–500
Time0.3–2 h

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

Parts involved

spark plug cyl 1ignition coil cyl 1ion sense module

Related codes

P2890P2891P2893P2896

References: law.cornell.edu, saabwisonline.com, en.wikipedia.org.