Yeah it is. Instead of pushing a burnt charge out the back it'll be spitting an unburnt charge down the intake.

If you'd run it backwards for any length of time it's possible to set fire to the intake system but unlikely to happen unless you were running it downhill a long way or, as I've seen, when a contractor was putting in a new dyno at work they got their wires crossed so the dyno tried to run backwards.

More you describe it the more it sound's like that.

There'll be some kind of feature on the crank that will be picked up by a sensor to instruct the ECU where the crank position is. There'll be another on each cam-shaft that has some level of variable timing (the ones I use are on intake only since it's intake only variable timing) to let the engine know where they are. If the ECU gets those signals in the wrong order (such as it's running backwards) it'll go into back-up mode.

 

Thanks all. I've found out how to reset the ECU, so will do that tomorrow and hopefully that'll be the end of it.