PEPS

📖 YOUCANIC Automotive Glossary

PEPS (Passive Entry Passive Start), also known as smart key, keyless entry/start, or proximity key, allows the driver to unlock the doors by touching the handle and start the engine by pressing a button — without physically inserting or pressing the key fob. The system uses low-frequency (LF) antennas around the vehicle to detect the fob’s proximity and radio-frequency (RF) communication to authenticate the fob’s encrypted code with the immobilizer system. Multiple antennas detect fob position to determine whether it is outside (unlock doors) or inside (allow engine start).

Common PEPS problems include key fob not detected (weak fob battery — the most common cause), intermittent detection (antenna module failure or wiring), unable to start with fob inside (dead fob battery — hold fob against the start button or designated spot), and relay theft vulnerability (criminals amplify the fob signal to unlock and start the vehicle). The YOUCANIC UCAN-II reads body module and immobilizer codes related to PEPS faults and may support key fob programming on supported vehicles.