51259230061 Spark Plug

Genuine MAN spark plug for CNG and LNG gas-powered MAN commercial vehicles. Mounted in the cylinder head, it initiates combustion by producing a high-voltage spark across the electrode gap at each firing event. Gas engines require plugs with tighter electrode tolerances than diesel equivalents — this unit meets MAN OEM specifications for gap width, heat range, and thread geometry. Compatible with MAN gas bus and truck engines in the D08 and D20 families. Gas engines typically require more frequent plug changes than diesel due to higher combustion chamber temperatures and the different chemistry of gas combustion — consult the MAN service manual for the specific interval applicable to your engine code. Symptoms of a worn or fouled plug include rough idling, misfires under load, increased gas consumption, and failed emissions tests. Always replace plugs as a full set across all cylinders. Torque to the value specified in the engine workshop manual to avoid thread damage in the aluminium cylinder head.