Helpful, knowledgeable in their diagnosis of my vehicle. I came in with 4 different codes from the smog people. I braced for the price when Darrel came to talk to me and was relieved that my problem was as simple as the wrong oil used by the people who did my oil change. He explained each code and said that if we could set P0014 by my driving my vehicle to reset the monitors that I could probably pass smog and we could work on the other 3 codes at a later date.