It will be fine mate. Make sure you do it whilst the engines running, soak in TFR, keep the lance away from the air filter and electrics if you can and you shouldnt have any problems mate. Try and leave it running for half an hour or so afterwards with the bonnet up too. Modern cars can take a good hammering with the jet wash/steam cleaners.

I used to steam clean 20+ cars a day, i used to give them a good going over without problems. Probably had one every week or so run a bit lumpy for a while afterwards but they were citroens and fiats so not to worry.