No 6. Timing belt failure
The timing belt controls the timings of your car engine’s valves. These belts must be periodically replaced at the manufacturer’s recommended distance and/or time periods. Failing to do so can result in complete breakdown or catastrophic engine failure which definitely can prevent the car from starting.
No 5. ECM/PCM failure
The ECM or Engine Control Module is actually the brain of your vehicle. It collects information from various sensors from the car and then sends out signals to items such as fuel injectors and timing to keep the engine running at its best for performance and fuel economy, whereas, PCM or the Powertrain Control Module, stops your engine RPMs from reaching critical levels.
If the ECM or the PCM fails then definitely it’s the one preventing your car from starting.
No 4. Faulty alternator
The alternator’s job is to charge up your battery. If the alternator isn’t providing voltage, then your battery simply cannot hold the power sent to it and it won’t certainly be able to send any current to the engine. If the alternator is faulty then this is the culprit behind all the trouble and needs immediate replacement.
No 3. Faulty crank sensor
The Crank Sensor, also known as the CPK, or crank position sensor, is responsible for making sure that the engine cylinders fire in the proper order. Or more specifically it monitors the position or rotational speed of the crankshaft. If your car won’t start it might be a good thing to check for a bad crank sensor.