Not sure if your smog guy mentioned this to you? But did you disconnect the battery or erase any obd codes prior to taking it to get the smog check done? I had a similar problem when I had to do mine last year... Not that it wouldn't read anything when connected to the obd... By my smog guy said that I needed to drive the car in the fwy for about 15-30 to activate all my emissions sensors so that my ECU could record them in order to take the test. You can try that out and see if it helps?
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