Transponder chip identification.

The chip family inside the head of your key determines whether the immobilizer will accept a new fob. Match the chip and you're 90% of the way to a successful pairing.

45 vehicles PK3 (Passlock III) GM (in-house) · 40-bit fixed 548 vehicles PCF7936 (Hitag2) NXP · Hitag2 (96-bit) 60 vehicles PCF7937 (Hitag2 Extended) NXP · Hitag2 + 80-bit 121 vehicles PCF7945 (Hitag-AES) NXP · AES-128 280 vehicles PCF7952 (PEPS) NXP · AES-128 441 vehicles PCF7953 (Hitag-PRO) NXP · Hitag-PRO (AES-128) 70 vehicles PCF7961 (ID46) NXP · ID46 (proprietary) 110 vehicles PCF7938 (ID47 / Hitag-3) NXP · Hitag-3 (AES-128) 158 vehicles Texas 4D63 (40-bit) Texas Instruments · 40-bit DST 105 vehicles Texas 4D63 80-bit Texas Instruments · 80-bit DST 72 vehicles Texas 4D67 Texas Instruments · 40-bit DST 48 vehicles Texas DST80 Texas Instruments · 80-bit DST 132 vehicles Texas DST-AES (8A) Texas Instruments · AES-128 70 vehicles Megamos AES EM Microelectronic · AES-128 63 vehicles Megamos 13/93 EM Microelectronic · Crypto-1 / 96-bit 70 vehicles Texas 4D62 Texas Instruments · 40-bit DST