Typical Ford Focus FAULTS
▶ If the battery goes flat overnight, look for the Body Control Module (BCM) behind the glovebox and a connector plug labelled C6 engine, which may be corroded due to water ingress. Also check the washer pump plug inside the offside front wheelarch, which can draw (capillary action) screenwash up the wiring and into the aforementioned BCM. Ford has devised a repair for this, which includes a new BCM, washer pump and plug. The BCM is coded to the vehicle. Mark at AES has found this problem only applies to the 2014 model year Focus, but not solely the Ecoboost engine.
▶ Fault code P0420 is for cat efficiency and Mark says it always means the catalytic converter has failed, but other problems have caused it, such as a misfiring coil that has been left for too long – and let too much fuel through, damaging the cat. If the high-pressure fuel pump leaks petrol into the engine oil (the pump is operated by the camshaft so petrol can get through), the petrol vapours in the oil will filter through the breather system and contaminate the catalytic converter. Check the engine oil level hasn’t risen (caused by petrol being added to the oil) and if a fault code P2188 is raised, it means the fuelling system is too rich, which could be caused by fuel vapours feeding into the cat. Note that the emissions test at the MOT will help to identify whether the cat is in good working order and may identify some of these problems we’ve outlined.
▶ The timing belt runs through the engine oil and can break up if the wrong oil has been used or petrol vapours are contaminating the oil (see Fault 3). A fault code P0106 relates to an inlet manifold/boost pressure fault. This can be caused by bits of timing belt blocking the vacuum pump, so vacuum to the boost control solenoid is lost and thus turbo boost pressure is also lost. Potentially you can also lose brake servo pressure – the brake pedal will feel hard when pressed.