help please esp light

[roy2001]

My esp light has come on on the dash it seems to be doing it intermittantly , my car is an 04 a4 1.8t cabriolet, can anyone give me any pointers as to what could be the problem thanks

[bez101]

could be anything
get the codes read

[NikB]

Mine came on along with the engine management light and turned out to be the brake pedal switch and again on it's own and was an abs sensor

[roy2001]

put my code reader on the car there are no fault codes stored, got another new brake pedal switch however when i got it home it looks different and the part numbers are not the same my original is 3bB0 945 511 and the new one is 1k2 945 511 the wiring fits correctly in the plug however wont turn the brake lights on and off. Now i have swapped parts over when i put original part back on when i turn the ignition on the brake lights come on immediately even though everythin looks set correctly ie pin in line with brake pedal and slightly compressed when not pressed etc