This is a first for me, when I press the windscreen wash button on the stalk it cuts the engine... No matter what speed!

Any ideas?

Does the windscreen washer acually work when this happens ? I'm thinking there may be a short circuit and the washer circuit that reduces the system voltage so the engine electronics stop working.

Possible bad earth behind headlights.

Scan for codes first.

It does yes, also no fault codes related to that.. Its away at the mechanic for a couple of ignition coil and lambda codes.. who knows, maybe it will be okay when I get it back!