Car Won't Start — Diagnose Crank No Start, Click No Start & No Crank

Car Won't Start — Identify the Symptom

When your car won't start, the first step is identifying exactly what happens when you turn the key (or press the start button). The behaviour tells you which system has failed:

Cranks but won't start: The starter motor spins the engine, but it doesn't fire. This is a fuel, spark, or compression issue.
Clicks but won't turn over: You hear a clicking sound but the engine doesn't crank. This is usually a battery or starter motor issue.
No crank, no click, completely dead: Nothing happens at all. This is an electrical issue — dead battery, faulty ignition switch, or broken circuit.

Cranks But Won't Start

If the engine cranks normally but doesn't fire, it's missing one of the three things needed for combustion: fuel, spark, or air.

Common causes:

No fuel — Empty tank, failed fuel pump, clogged fuel filter, or blown fuel pump fuse.
No spark — Failed crankshaft position sensor (P0335), faulty ignition coil, or failed ignition module.
No air — Severely clogged air filter (rare but possible).
Timing issue — Timing belt or chain has slipped or broken.
Flooded engine — Too much fuel in the cylinders (hold the accelerator to the floor while cranking).
Immobiliser fault — The car doesn't recognise the key. Try a spare key.

Clicks But Won't Turn Over

A rapid clicking sound means the battery has enough charge to activate the starter solenoid but not enough to turn the starter motor. A single loud click suggests a faulty starter motor or solenoid.

Common causes:

Weak battery — Test the battery voltage. Below 12.4V it may not have enough cranking amps.
Corroded battery terminals — Clean the terminals with a wire brush and baking soda.
Faulty starter motor — The starter motor itself has failed. Tapping the starter with a wrench while someone cranks may temporarily work.
Bad ground connection — Corroded or loose ground cable between the engine and chassis.

Completely Dead — No Crank, No Click

If absolutely nothing happens:

Dead battery — The most common cause. Try jump-starting the car.
Faulty ignition switch — The electrical switch that sends power to the starter circuit.
Blown main fuse — Check the main fuse box for blown fuses related to the ignition system.
Neutral safety switch — The car thinks it's not in Park/Neutral. Try jiggling the gear selector.
Anti-theft system — Some vehicles lock out the starter if the immobiliser is triggered.

When to Call a Mechanic

Try these quick fixes first: jump-start the battery, check fuses, try a spare key, and clean battery terminals. If none of these work, the issue likely requires professional diagnosis.

A mobile mechanic with a proper scan tool can test the fuel pump, ignition system, and starter circuit on the spot. Expect to pay $80-$150 AUD for a diagnostic callout.