No-start? Three families of cause. All three are measurable in the driveway.

What it usually proves to be (in order)

1. 1No-crank: starter, battery state, ground, or an immobilizer signal — not a new car needed
2. 2Fuel side: pump relay, inertia switch, injector pulse — a test light settles it
3. 3Ignition/timing side: crank-position sensor (P0335) kills spark with no warning
4. 4A weak battery that cranks almost enough and logs phantom U-codes

What a parts-changer will tell you

Swap the starter ($300–$600), then the battery, then maybe its the fuel pump. Meanwhile the crank sensor that intermittently drops signal — the actual fault in countless no-starts — is never scoped.

Typical guess-and-swap cost: $300–$900 in swapped parts when the real fault was a sensor, relay, or wiring

The test that proves it

Verify spark and injector pulse first (two minutes), then battery voltage-under-crank, then scope the cam/crank pattern. A no-start is a decision tree, not a lottery.