E36 325TDS Touring Engine fault light HOT START ONLY?

Starting cold is unchanged ... better with 2 hits on the heater timer starts
fine runs
well, no light.

It used to need a few cranks when hot but now fires like a petrol first
compression hot. Then does a little rev to about 2K rpm. and settles back to
idle. with the injector light on.

ONLY when started hot I get the light.
Diag. states ELAB (Idle valve) short to ground.
Where is it on the turbo diesel?

It also mentioned a speed sensor fault ...
I don't know where that is on these little 3s I have always had E34s!
Could this screw up consumption with an Auto?

Not had it long!

Thanks gurus!
Garry
Manchester
UK