I have a 1997 luxury sedan. My car passed all tests except for the OBD-II (On-Board Diagnostics) computer scan. The shop owner told me that the sensors that monitored the car were not initializing properly and I would have to get my computer fixed and do a retest ($18). As a precursory measure, he told me to drive the car for fifty miles and then come back to see if the computer had reset its memory. I did this the same day and he again said that it failed to initialize.
I took my car to an acquaintance who does auto work and hooked up his OBD-II scanner to my car's computer. Amazingly, the monitors DID initialize and indicated that there was a clog in my EGR valve, which means that the computer was working fine. After the EGR valve was cleaned, all monitors passed the ODB-II scan. There was, however, never an indication that the computer was faulty.
When I went back to get a retest, I told the owner that I had done an OBD-II scan and that the monitors initialized and indicated a single error. He got extremely defensive and told me that I must be wrong. I reiterated what I had said before and he shook his head and wagged his finger at me, insisting that my computer was broken.
Well, perhaps my computer was broken at the time of the test and then magically restored itself in a matter of hours, but I find that highly unlikely. I will refrain from any undue accusations, but the least I can say is that the OBD-II scanner at this shop is either broken or inaccurate.
I will never go to this shop again.