I can also vouch for the paper clip test. Literally takes a couple of minutes at the most and is always spot on if you have the correct fault code list. Dont waste your money on tech2 tests at the dealers!!! Search for paper clip test on google and im sure youll come accross it easily enough. I think theres a good guide on cavweb. Its saved me a fortune in the past and better than the tech2 in my opinion. My vauxhall dealer diagnosed my gte with a faulty ecu, but the paper clip test showed up as low voltage on one wire, changed the wire and was as good as new.