Engine Will Not Start: Petrol Versus Diesel

Silent Starter

On an automatic, the selector must sit in P or N or the inhibit switch blocks the crank. Clean and tight battery posts under the left-hand cover. Headlights on, then try to start: if the lamps collapse, charge or jump the battery and find the drain later. Check the earth strap and the starter feed. A chewed ring gear or a failing solenoid clicks or grinds instead of spinning the engine.

It Cranks, It Does Not Fire

Confirm real fuel in the tank. Then decide petrol or diesel, because the next five minutes diverge.

• Petrol: PATS must drop when a coded key goes into the barrel. A cut key with no chip cranks forever. Damp coil-on-plug packs and worn or wrongly gapped plugs are common after a wet night. Look for broken ignition wiring and a vacuum leak at the throttle body or manifold that lets the engine fire once and die. Fouled plugs after a short run mean the fouling cause is still there.
• Diesel: Cold starts need a healthy pre-heat system. Air in the fuel after a filter change or a dry run stops injection until the lines are bled. A choked fuel filter or a weak pump delivery leaves a fast crank and no combustion smell. Major mechanical failure (cam drive) is rare next to glow and fuel issues, but a dead quiet valvetrain while cranking is a stop-and-investigate moment.

Quick Bay Pass

Battery state of charge, under-bonnet fuses for ECU and injectors, immobiliser behaviour, then fuel smell at the rail or filter housing. Do not throw a pump or a starter at a car that only needed posts cleaned or a glow relay. Roadside starting detail lives under W-401 if you need the silent-versus-crank split in one place.