On 4 occasions whilst driving at exactly 70 mph on motorway or dual carriageway the revs on my xm dropped suddenly for around 2 seconds almost as if the car had totally switched of and then as quick as it dropped came back to normal. I find it also most bizarre that it happened within a mile of the same section of the A1 near darlington once southbound and once northbound though on different days, and has since happened on a stretch of the A19 near middlesbrough in similar circumstances, any ideas?

mine used to do this just as it reached operating temperature, it turned out to be a bad earth in the ecu box, its a small brown wire that is bolted onto the bracket the suspension and engine ecu are fixed to and is the earth for the oxygen sensor, make sure its tight and clean, if not, sounds like amplifier module breaking down, but try the earth wire first. thing is with these damn intermittent faults is they are such a sod to find! but good luck , hope its cheap

Dean

Very disconcerting. I had a hard failure in on middle lane of motorway a few years back just after ignition module was replaced, either the cable clip was lost or not replaced correctly and came off. Luckily nothing close in the slow lane so I managed t get to hard shoulder ok.

Of course, the military etc CLAIM their electronic monitoring has no effect on cars etc but who knows, maybe they didn;'t test on Xm's :--)