Why won’t my car start?

Start with the sound, not the parts

Turn the key or press the button once, and listen. Does the engine turn over (crank)? If it does, does it crank strongly or lazily? If it does not, is there a click, a rapid rattle of clicks, or nothing at all?

That single observation splits a no-start into a power supply problem, a starter problem, a control circuit problem, or an engine that is turning over but not firing. Guessing without that split is how batteries and starters get replaced for nothing.

What each symptom suggests

• Slow, lazy cranking: usually low cranking current — a discharged battery, a battery near end of life, or corroded and loose connections.
• One loud click then silence: the starter solenoid is engaging but the motor is not turning the engine.
• Rapid clicking or buzzing: voltage collapsing under load, most often a weak battery or a poor connection.
• Nothing at all, with a dark dashboard: no supply, or the ignition switch is not passing power.
• Nothing at all, with a normal dashboard: power is present but the start request is not reaching the starter — relay, safety switch or immobiliser.
• Strong cranking but no fire: the starting system is doing its job. The engine is missing fuel, spark or compression.

What a jump start tells you

If the engine starts and keeps running with a jump, the battery was too low to do the work. That still does not tell you why it was low — a failing battery, a charging fault, or something drawing power while parked all produce the same result.

If a jump changes nothing, extra power was not the missing ingredient. Look at the starter, its control circuit, or the engine’s ability to fire.