My 2006 Prius showed the Red Triangle of Death. My OBD2 phone app connected to the data port via bluetooth. I saw the code to replace the hybrid battery. Car was driveable to their location. With no appointment and in less than 24 hours, I was back on the road. The mid 30s mpg that the car has slid down to over the past few months is gone. Now getting 45 - 47 mpg with 212,000 miles, and my wife's mpg is even better than that. Good product, fair price. I'll check back in a month to update and potentially add the final star.