Clutch B disengagement pressure is below the calibrated minimum. Clutch may not separate cleanly under load.
Medium severity. Can I keep driving?Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
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
Most likely causes
- Hydraulic pump output pressure low
- Pressure regulator characteristic drift
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: hard
- It can trigger limp mode.
What each character of P285A means
- P: Powertrain: engine and transmission
- 2: Generic code: same on every make
- 8: Transmission
- 5A: Specific fault in that system
Frequently asked questions
Can I keep driving with code P285A?
Drive gently to a repair shop. If it slips, you hear clunks, or it loses its gears, do not keep driving.
What causes code P285A?
The most common causes are: hydraulic pump output pressure low; pressure regulator characteristic drift.
Related codes
Sources
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.