General Crankshaft sensor

[Dobby]

What does it do? it came up on a diagnostic check on the car so i bought one from a scrappy for £15

Haven't fitted it yet cause have no idea how to, but would this failed crankshaft cause the engine to sound like a tractor when running idle?

 

[jug]

it tells the ecu where the pistons are, and that information is used to control the timing of sparks. if the sensor was broken i'd be very surprised if the car ran at all, if it does start you're just getting lucky as the wasted spark on 2 or more cylinders just so happens to be coming at the right time. it would be very rough though.