Powertrain, generic (extended)

P286B Clutch A Pressure Engagement Too High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P286B means the pressure applied to clutch A during engagement exceeded the level the control unit had planned. A clutch pressed too hard closes abruptly, which shows up as a jolt, a harsh launch or a shunt through the driveline. No manufacturer documents P286B publicly; the basis is CARB 13 CCR 1968.2, which asks for functional monitoring of automatic transmission controls. GM's 2023 Corvette dual-clutch software performs a comparable check under another number: clutch 1 is reported as a Type A fault under P2855 when its measured pressure rises clearly above the model, for example more than about 1.2 bar above the hold level for 300 ms. Typical causes are a sticking pressure control valve, a sensor that reads high or adaptation values lost after a repair.

Likely causes

Clutch A pressure control valve sticking towards high output
Clutch adaptation values missing or wrong after repair or software update
Clutch pressure sensor reading higher than actual

Symptoms

  • Harsh launch or jolt when clutch A closes
  • Clunk through the driveline during shifts
  • Warning lamp, possibly limp mode

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–3,500
Time0.5–8 h

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

Parts involved

clutch aclutch actuator apressure regulator

Related codes

P2873P286CP2857P2855P286E

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