Powertrain, generic · Transmission

P081F Brake Transmission Shift Interlock (BTSI) Signal Correlation

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

The brake transmission shift interlock (BTSI) is a solenoid or actuator that locks the selector in park until the brake pedal is pressed, as US rule FMVSS 114 requires. 'Signal correlation' is the plausibility check between the interlock command or feedback and its input signals – brake switch and selector position: for example the lock released without a brake signal, or still active although the brake is pressed. The selector then cannot leave park, or it moves without the brake and the safety function is missing. Electrical faults of the lock solenoid have their own codes P0928–P0931. No manufacturer document with P081F is available to us; a GM service update for the 2016 Malibu and 2016–17 Volt explains the part and the 'won't shift out of park' complaint. CARB may exempt such safety parts from monitoring.

Likely causes

Brake lamp switch misadjusted or faulty
Interlock solenoid or locking mechanism sticking
Wire or connector to the selector
Selector module, control unit or software

Symptoms

  • Selector cannot be moved out of P
  • Selector moves out of P without the brake
  • Warning about brake or range

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–500
Time0.5–2 h

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

Parts involved

shift interlock solenoidbrake switchgear selector

Related codes

P0928P0929P0571P0703P0850

References: law.cornell.edu, static.nhtsa.gov.