Knock Sensor Knock sensor detecting combustion knock so ignition or injection timing can be corrected 4U "20254MR" - Not availableCITROËN - Xsara, Saxo, Xantia, Jumper; PEUGEOT - 206, 406; FIAT - Ducato; OPEL - Astra H; DAEWOO - Korando, Musso; ...