What can cause cranks but will not start?
Cranks but will not start can come from more than one engine & drivability branch. Operating conditions, warning behavior, scan data, and physical tests are needed to separate the supported cause from look-alikes.
Plausible causes
- Engine operating-state fault
- Fuel, air, or ignition delivery
- Mechanical compression or timing
Useful next checks
- Record whether it does not crank, cranks without starting, starts then stalls, or runs poorly. Capture the exact warning, temperature, load, sound, and DTC freeze-frame without clearing codes.
- Battery and cranking voltage-drop test
- Full-module scan with freeze-frame and cranking RPM
Sources and method
This answer provides hypotheses and a verification plan, not a component verdict. Exact repair procedures require authoritative service information for the specific vehicle.
Engine Misfire Diagnostic Aid · NHTSA / Volkswagen