it can be checked just opening the bonnet. there is little sensor in near crankshaft, pointing towards of 4 pins in the crankshafts v-pelt pulley and it needs to have 0.6-1.0mm clearance for the pins. it also needs to be sturdily in its mounting bracket. those 4 pins are at 90degrees apart from each other. check that there are no damage on the pins.