The 'Black Socket Trick'

Machines that read fault-codes aren't cheap, starting at about £350 and running into thousands for a pro one, so its good to know that Subaru, like a lot of other Japanese marques, builds in a gizmo that lets us check the codes ourselves, at the roadside if we need to.

There is a male and female plastic connector hanging loose just behind the trim under the steering column, just behind where the socket for the OBD-type reader is. The connectors are unplugged from each other by default and clipping them together bypasses the circuit for the OBD socket so the car's own can be used.

Once the two connectors are clipped together, turn the key so the ignition is fully on, without starting the engine. The CHECK ENGINE light will do a series of long and short flashes. First come the long flashes [about 1 sec each], which denote the first digit of the fault-code and then quick flashes, which denote the second digit. i.e two long and three short would be a fault-code 23.

Here is the LIST OF FAULT CODES that work with the system.

[The car still works with the connectors left plugged in, but its probably best to unplug them to save the car doing a check every time you start up and make the OBD socket accessible if you take the car in to a garage. Not that any ScoobyLab fan should ever have to!]