I experiencing same problem as you described about saab 9-5 check engine keeps coming back and going off.
Did you find a solution to the problem. could you please share it with me?
Originally Posted by meswalk
I have had a strange problem with my Saab for the past three years. The check engine keeps coming back and going off. Specifically, it often comes back (if it has disappeared) when I fill up gas. I got the following codes using an OBD II reader P1312 P1314 P0455 P0340. I was told the gas cap and the ignition module cassette needed replacement. I changed the ignition module twice along with spark plugs to no avail. I have also changed the gas cap (albeit with a non-OEM one). I was wondering what could still be causing the CEL. More importantly, I am quite puzzled as to why it keeps switching off and coming back on. Any inputs will be highly appreciated.