I have a run of the mill OBDII scanner from Amazon. I connect it to my phone's (Android) app, Torque PRO, via Bluetooth.
I have been using it for 22-months. No problems whatsoever. My car never returned a fault code. Check engine light never turned on. For 22-months, I was completely happy with the car as it gave me 0 problems and it has performed really well.
I do my oil changes in drive thru, big-box oil change shops.
Last night, I decided to go to my car's dealership for an oil change. They said my car has a recall for the rear O2 sensor software; that it needs to be reprogrammed. I said, "OK whatever, do what you have to do, as long as I get my regular oil change and go home after."
2-hours later, after flashing the ECU with the recall "fix," they say the car won't start, and they suspect the ECU is dead, implying that my OBDII device is the culprit because it messed up the ECU.
My question is, are they correct to say that these OBDII devices can mess up the ECU? To my knowledge, they only read, and cannot write to the ECU. It is my belief that they messed up flashing the ECU with the software update.