P - Park
P/B - Power Bakes
P/N - Part Number
PCM - Powertrain Control Module
PCV - Positive Crankcase Ventilation
PFI - Port Fuel Injection
PGM-FI - Programmed Fuel Injection
P/N - Park/Neutral
PPM - Parts Per Million
PRNDL - Park Reverse Neutral Drive Low
PROM - Program Read Only Memory (chip)
P/S - Power Steering
PSI - Pounds Per Square Inch
PTC - Positive temperature coefficient
PWR. - Power