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Resources for Tuners

GM/Opel seed key calculator

Calculate a 2-byte or 5-byte response key. Select a known GM5 ECU or enter a manual algorithm ID.

Supported GM5 ECU presets: E84, E39/E39A, E78, E80, E82, E92, E98 and E90. View ECU support and seed formats.

Sign in to calculate and copy a response key. Sign in to the GM seed key calculator.

GM2 needs four hex digits; GM5 needs ten. Manual GM5 records require a final byte 00–0A. Keep the received byte order.

Named ECU choices are temporarily unavailable. Manual algorithm entry is available.

Algorithm 0–255. Required for manual single-key calculations.

Required only to match a captured seed/key pair.

Use the module's known ECU preset or algorithm and table. A match from one captured pair can be ambiguous; confirm it against further captures before use. Module programming uses your diagnostic equipment.