Some 2012 Honda Civic models may illuminate the Check Engine light and log one or more of the following trouble codes in the PCM: P0300, P0302 and P0303.
According to Honda, one possible cause for the trouble is that the crankshaft position sensor was replaced, but the pattern relearn procedure was never performed or allowed to complete.
To make the correct diagnosis, hook up your scan tool and head to the data stream.
If the misfire counts for all cylinders are zero, look at the CKP Pulser F/B Learn PID.
If the info next to the PID reads complete or Yes, this information doesn't apply; continue troubleshooting until the cause of the code(s) is found.
If the info reads incomplete or No, go ahead and perform the relearn on the crank sensor with your scanner.