less likely it is the abs module, but possible. usually, there is only DSC light come on (brake and abs light do not come on) if it is the abs module fail. most likey it is the steering wheel sensor or abs sensor (someone call it wheel speed sensor, officially called pulse generator, abs). if it is abs sensor, you might notice that your car applies brake unintentionaly when you start to drive before lights come on after each time you start your car. did you do any job on front suspension before?

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--2004 E53 X5 4.8is - ECE version; right hand drive; Located in Hong Kong; ext. black sapphire metallic; int. leather black; adaptive dynamic bi-xenon headlights; 16:9 onboard monitor w/o navigation; 20" genuine BMW Y-spoke 214 wheels with Bridgestone Dueler H/P Sport tires; Int. rear view mirror w/ compass.