Very common fail on Mondingoes is the Turbo Actuator (electric servo type)

The flashing glow plug lamp is a common sign the actuator is on the way out

When the flashing light occurs again pull over when possible turn off engine and remove key count to 10 and restart this resets the position of the actuator and off you go again

As for OBD readers some will only read the MIL (Malfunction Indicator Lamp) and not manufacturer specific warning lamps such as the Ford Glow plug lamp

An ODB reader may give a code but it can actually bear no resemblence to the fault that is causing the problem

Personally I use Snap-On Modis but also have access to various other "machines" to help in diagnosis