Powertrain, generic (extended)

P2859 Clutch A Pressure Disengagement Performance/Too Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2859 concerns the release side of clutch A: during a ratio change the control unit sees that the pressure handover is not working as planned, so the old and new power paths overlap or the wrong ratio persists. Mitsubishi's Mirage CVT shows how this is tested. With the first auxiliary ratio commanded, a fault is logged when the ratio stays within 10 % of the second ratio (0.900–1.100) for 0.5 s, if it leaves the plausible window (0.911 or less, 2.732 or more) for 0.2 s, or if the high clutch pressure switch reads on for 1.5 s at up to 10 km/h while its target pressure is zero. Nissan lists P2859 among the Kicks/Versa CVT pressure codes, and Mercedes-Benz calls it a general malfunction of multidisk clutch 1 on the 8G-DCT. Harsh or doubled shifts follow.

Likely causes

Outgoing clutch not venting in time, so both elements carry torque
Sticking pressure control solenoid or valve in the valve body
Clutch pressure switch reporting pressure that is not there

Symptoms

  • Harsh, doubled or tied-up shifts
  • Wrong gear stage held, engine speed too low or too high
  • Transmission warning and emergency program

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€150–4,500
Time1–10 h

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

Parts involved

clutch aclutch actuator atransmission pump

Related codes

P285AP2857P286CP286FP0876

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.