Just come on randomly,can't see any codes using the dash trick,it's come on before but went after I switched the car on and off.cracked pipe or worse?

2800rpm is where it stops.

Also note the system fault appears when you turn the key so the dash lights up before even starting the engine.read it could be maf,egr valve turbo pipes etc.hopefully it's the maf as anything else looks mega expensive

It could also be a faulty instrument cluster. If no DTC codes are stored the problem is most likely caused by the instrument cluster. This is a known problem for the MK2/MK2.5 instrument cluster. Due to bad soldering connections of the circuit board of the instrument cluster there can be an (temporarily) open connection. This can result in a burning engine light and the engine managemant going into limp home mode.

You should diagnose the car with a suitable diagnostic interface. Not all fault codes in the instrument cluster menu. If no codes are storedthe instrument cluster would be the first suspect.

if its engine then the dash trick may not show up codes invest in an obd reader for £20 which will read codes and reset mil lights

Will the obd reader read any code on it,how comes they charge 45 quid or so for a diagnostic read at garages

depends where the fault is, an OBD code reader will normally only query the ECU, something like F-Super, can talk to most of the computers (ABS, ECU, Instrument Cluster etc).

the "diagnostics fee" IMHO is a rip off anywhere. to plug the car in and read an error code takes no effort at all, however, if they are plugging it in, reading the codes, looking at the readings, and actually (god forbid) having to THINK about where the error might be, then perhaps a small fee is in order. It peeves me off when any garage claims a diagnostics fee for a 2 minute connection to the PC.

My mate had this same revving problem with his BMW, Does the engine smell like its running lean? . He had a majority of the Sensors checked, bought new spark plugs, new coil pack, new HT leads, hours of pondering on what it could be. Still the same problem. This may not be a technical answer (At all lol) but out of rage he started revving the nuts out of it and after a minute or two it "Cleared" and is now working perfectly. He thinks there was a blockage in the exhaust or cat, could be worth looking at?

Mum drove the car today to work (it's only a mile n half drive,on the way back she went over a couple of bumps and the lights gone off,so sounds like a dodgy connection to me.

You could try to wiggle the connector at the back of the instrument cluster. If the problem returns it is definetely caused by bad soldering connections of the instrument cluster. This can be solved pretty easy by resoldering the connector pins to the circuit board. If you are handy with a soldering iron you can do this yourself easily.

Light came on,banged the top of the dash with my hand and it went off

In most cases resoldering the connector to the circuit board of the instrument cluster will solve the problem.

Until now I repaired at least 15 Focus MK2/MK2.5 instrument clusters with this problem by resoldering the connector to the circuit board. The easiest way is by using a hot air soldering iron but a normal soldering iron with a small tip will do the job as well.

Never used a soldering iron in my life lol,is it possible to take the cluster out and have a look myself to see if that's the problem?saves me taking it somewhere for them to pull it out and charge me then tell me it doesn't need soldering

As it's come back on again,I got it to go off a second time jiggling wires in the engine bay and banging the top of the dash again(not sure which made it go off).its come back on but can't get it off this time

What I don't understand though is the light had gone off and stayed off for 8 days.surely it would be more intermittent than that.

Had it diagnosed :fault codes p0670 glow plug module control circuit u0422 invalid data received from instrument panel or body control. He cleared the codes but came straight back on.any thoughts?