Go somewhere quiet and put your ear close to each sensor , turn ignition on dont start car press the pdc sensor in car and walk round and listen to each sensor you should hear clicking like that of the click on a gas stove lighter....one sensor out means all system down....then it is either the sensor or cable cut to it, or even the harness totally disconncected behind bumper

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E53 X5 3.0d SUV prod.date 11/2004 eng.variant M57N Europe Right hand drive N