Powertrain, generic · Transmission

P08C9 Pressure Control Solenoid M Control Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Meant for a control circuit of pressure control solenoid M that is not open or shorted but behaves implausibly, for instance a coil current that does not follow the command. No manufacturer documents this code publicly. GM, which uses letter M for synchronizer actuation valve 1 of the Corvette dual clutch, publishes only open, low, high and the two hydraulic codes for it; its tables do describe a current check that compares target and estimated current (more than 70 % for 60 ms or more than 400 mA for 300 ms), but without naming P08C9. CARB requires monitoring of transmission solenoids. Possible causes are a coil with drifting resistance, contact resistance or supply voltage problems; shift quality may suffer.

Likely causes

Coil resistance out of specification
High contact resistance at connector pins
Unstable supply voltage to the transmission module

Symptoms

  • Check engine light on
  • Uneven shift quality

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–2,500
Time0.5–5 h

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

Parts involved

pressure control solenoid mwiring harness

Related codes

P08C8P08CAP08CBP08C0P27BE

References: law.cornell.edu, gsi.ext.gm.com.