OBD-II reference

All 9.533 generic OBD-II codes, explained in detail.

Causes, inspection steps and sources — a comprehensive DIY archive. Created and maintained with love for the detail. Good luck and have fun!

Powertrain generic / SAE

P081F

Brake Transmission Shift Interlock (BTSI) Signal Correlation

The Brake Transmission Shift Interlock prevents shifting out of Park unless the brake pedal is pressed. The TCM compares the brake-pedal input to the BTSI solenoid command and detects an inconsistency — for example shift permitted while brake not pressed, or interlock active while brake is pressed.

SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number8 / 1F

Possible causes

  • Stuck brake pedal switch high
  • Mis-adjusted BTSI mechanism medium

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

Inspection / repair

  • Difficulty: medium
  • DIY: shop recommended
  • Estimated cost: 80–500 €
  • Estimated time: 0.5–2 h
  • Component: btsi solenoid
  • Component: brake pedal switch
  • MIL / check engine light

Sources

References

How to read OBD-II codes

The first letter names the vehicle system, the second digit distinguishes generic from manufacturer-specific, the remaining digits group fault area and number.

PPowertrain: engine, transmission, emissions
BBody: chassis trim, comfort, interior
CChassis: suspension, brakes, steering
UNetwork: CAN, control modules, communication