Do not drive
It cranks but will not start
The starter turns the engine over briskly, but it does not catch. Sometimes it catches and dies.
With this symptom you should not keep driving: the trip will cost more than a tow truck.
What to look at in the live data
- Engine speed while cranking: if the app sees it, the crankshaft sensor is alive — and that is the most common cause of «cranks but will not start».
- System voltage while cranking: below 9–10 V the battery is to blame, not the engine.
- Stored codes: often the direct answer is already there.
- Temperature: in the cold the picture differs, and that is normal.
Common causes, cheapest first
- The battery: it spins briskly for the first seconds only.
- No fuel at the rail — the pump or its fuse.
- The crankshaft position sensor: a classic sudden death without warning.
- The immobiliser did not recognise the key.
- A snapped belt or timing chain — that one means a tow truck.
Codes that show up with this
P0335Crankshaft position sensor circuit malfunctionP0230Fuel pump primary circuit — malfunctionP0016Crankshaft/camshaft position correlation (bank 1, intake)
These parameters in the reference
Engine RPMControl module voltageCoolant temperatureFuel pressureFuel rail pressureFuel rail pressure (rel. to manifold)Hybrid battery pack remaining life
Lamps that may be on
Do it step by step
Three voltage readings answer the question of who is to blame: the battery, the alternator or the wiring.How to check the battery and alternator with the app
A symptom is not a diagnosis. The same sign comes from a dozen different causes — the readings are what tell them apart, not the feeling.
How the app helps
CarScan shows exactly these readings live, remembers the highest and the lowest value of the trip, and puts them into a report you can hand to a mechanic.