Mercedes C-Class W203 (2000-2007): known problems and buying guide

Before you buy

1. Start the car cold and listen for a metal rattle. Ask for proof that the chain, tensioner and cam sprockets were replaced together. A scanner reads camshaft codes. Bad result: a rattle, a check-engine light or no record.
2. Drive in drive and reverse. Shifts must be smooth. A sweet antifreeze smell or cloudy fluid is bad. A scanner reads gearbox codes.
3. On a lift, check the wheel arches, sills, lower door edges, boot lid and tailgate. Bad result: bubbling paint, holes or fresh filler.
4. Check the injector wiring under the valve cover for chafing, then start the diesel cold. Bad result: chafed wiring or a fault code. A scanner reads injector codes.
5. Check the boot for damp under the trim, and the sunroof drains. Test the rear and brake lights. Bad result: damp under the trim or a rear light that does not work.
6. Turn the key through all positions and start the engine. Ask whether the ignition unit was replaced and coded, and how many keys work. Bad result: a stuck key or a starter that does not respond.
7. On a lift, check ball joints, control arm bushes and tie rods for play. Bad result: knocks over bumps or uneven tyre wear.
8. Look for oil at the camshaft adjuster magnet valve and ask whether an oil-stop cable was fitted. Bad result: oil on the plug or wiring.