Before you buy a used Ford Focus (III).

Look out for: Low oil-pressure warning just before a loss of power; sometimes the engine seizes without warning. With no oil pressure the vacuum pump that assists braking can also stop working.

Ask them to check: With the oil-pressure warning, stop and do not restart. At the garage, check the belt and tensioner and look for debris in the sump and pump screen; use the exact oil Ford specifies and do not stretch the change intervals.

Look out for: Coolant loss, overheating and, if you keep driving, serious cylinder-head or engine damage.

Ask them to check: Check with Ford by VIN that the service action was done; watch the coolant level and stop at the temperature warning.

Look out for: Coolant loss with no visible leak, rough running on cold start, white smoke and, in serious cases, engine failure.

Ask them to check: Watch the coolant level; if it drops with no external leak, run a pressure and combustion-gas test and check the spark plugs. Ask Ford by VIN about warranty actions.

Look out for: The temperature rises, coolant is lost and, in extreme cases, oil sprays under pressure from a crack in the head with a risk of fire in the engine bay.

Ask them to check: Check with Ford by VIN that the recall was done; watch the coolant level and stop at the temperature warning.

Look out for: A pressure plate that breaks on manual EcoBoosts; batteries, alternators and boost control (2011); starter (2011–2014); at the roadworthiness test, springs and shock absorbers, suspension, lights, oil leaks already at the first inspection and exhaust; a broken cable in the tailgate hinge.

Ask them to check: Check every campaign by VIN; check oil leaks, suspension and lights; test the battery.

Look out for: Shudder or judder when pulling away, especially in traffic; gearbox-module faults that can stop the car starting.

Ask them to check: Read codes (e.g. P0900, clutch actuator), update the gearbox software and run the relearn drive cycle; if the shudder remains, replace the clutch. Ask Ford about campaigns or warranty extensions for the VIN.

Look out for: Filter regenerations at excessive temperature, a damaged filter and particle emissions above the limit: the car can fail the emissions part of the roadworthiness test.

Ask them to check: Ask Ford by VIN whether recall 24E06 is outstanding; check the filter and the regeneration history before the roadworthiness test.

Look out for: Hissing from the engine, diesel smell in the cabin, very dark oil between changes and, eventually, a failing turbo with smoke and loss of power.

Ask them to check: Check the injector washers and the turbo oil-feed filter. If the turbo is replaced, also clean the sump, intercooler and feed pipe, or the new turbo can fail again. Use low-SAPS oil.

Look out for: Particulate filter warning and power loss; rough idle from a dirty EGR; vibration and knocks when starting or in low gears (dual-mass flywheel); smoke or hesitation from injectors at high mileage.

Ask them to check: Read the DPF status and additive level, check the EGR and cooler, check the dual-mass flywheel at start-up and measure injector balance rates.