What does 'cranks but won't start' mean?
When a vehicle cranks but does not start, the starter motor is turning the engine, but the engine is not successfully beginning combustion.
Several systems can cause this condition, so replacing parts without diagnosis can become expensive.
Important areas to check
- Fuel supply
- Ignition spark
- Injector operation
- Crankshaft and camshaft signals
- Engine compression
- Immobilizer authorization
- ECU power and grounds
- Relevant diagnostic trouble codes
Why scanning the vehicle helps
A diagnostic scan can reveal stored codes and provide live-data information that helps narrow down the fault.
For some no-start problems, checking whether the ECU is receiving a valid crankshaft signal is especially important.