Master Cylinder Piston Position Higher Than Expected

Check these first

• A master cylinder piston resting too high from a mechanical fault
• A piston position sensor A that lost its calibration
• Trapped air holding the master cylinder piston off its rest point
• A brake pedal linkage that holds the piston too far in
• A failing master cylinder with an internal return spring fault

What to do next

1. Read the piston position sensor A value at rest on live data
2. Check the brake pedal linkage and pedal free play
3. Bleed the master cylinder if air is suspected
4. Run the piston position calibration with a scan tool
5. Replace the master cylinder if the piston rest point stays wrong
6. Clear the code and retest

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