Mk2 focus malfunction on motorway only

[Kjayvcg]

Just bought a 1.8 56 plate petrol runs great locally but 5 mins down the motorway loss in power as and engine malfunction light appears, once ignition  turned off an on immediately ok but only under 65 mph, ( managed to take junction slipway and back home through back roads). Car not yet been looked at but haven't had a problem since as not been used on motorway. Had oil filter replaced days before incident. No dash light displaying and runs great at moment on local roads?

[FatHead1979]

Well one of the common culprits for this type of fault on modern cars (the fuel filter) can be ruled out as your engine doesn't have a user serviceable filter, just a sort of "strainer" near the tank.  You really could do with having the DTC (error codes) read, some codes are recorded even if the condition that triggered them is no longer being met.

Often people have bought an ELM327 cable and used the free and very useful Forscan software to clear fault codes and monitor telemetry to try and diagnose a fault.

If you drive in a lower gear but rev it out to around 4000 RPM and hold it there, does it trigger the fault?  I ask because if the pump isn't able to deliver enough fuel to the engine I'd expect this kind of test to highlight if this was the case.  If it doesn't trigger the issue them maybe the fuel pump is okay and the fault/issue lies elsewhere.  Modern cars can behave all sorts of weird just from faulty data from a dodgy sensor.

[JONATHAN_11_80]

Does sounds like a fuel pressure related fault.