Car Scanner is free, but has some limitationa and adverts.
But...
£3.50 for a 6 month licence.
£5 for a year.
£6 forever.
Car Scanner ELM OBD2.
I think this is only on the iPhone, not sure. Try the free version then buy the ad free bit if it works.
If you have an Android phone, then I can't advise...