Powertrain Definition only Lights the check engine lamp

P2859: Clutch A Pressure Disengagement Performance/Too Low

Standardized SAE J2012 code · P28xx codes

What does P2859 mean?

Clutch A disengagement pressure is below the calibrated minimum. Clutch may not separate cleanly under load.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

  • Check engine or transmission warning light on
  • Harsh, delayed, or missing shifts
  • Possible limp mode (locked in one gear)
  • Slipping or shuddering during gear changes

Common causes

  • High Hydraulic pump output pressure low
  • Medium Pressure regulator characteristic drift

Likelihood is a general estimate across vehicles; your make and model may differ.

Add your car to see reports of P2859 on the same make and model first.

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