CEL (P0306) intermittent flash at start
 

Would anyone be able to explain why a CEL (P0306) would flash intermittently (meaning flash for a bit, then steady, then flash some more) during the first few minutes of operation (couple of miles) then remain steady? Another oddity: more often than not the engine runs smooth; have a few situations where rougher, misfire-like running occurs, but then it will go back to smooth a few trips later. This doesn't happen mid-trip but after a stop over.

Thanks to this forum, I've read quite a bit about the many things that could be going on. Just thought that these symptoms might help prioritize a plan of attack. Recently purchased the car. 44k, looks great, recently worked over by a quality independent shop. Was told previous owner didn't drive it enough or hard enough and carbon build up caused it to quit running. They claim they put 6k or 7k worth of work into it so I assume it's tuned up. Car has no other issues.

You might want tell us what the code decodes to, much easier to get advice. After looking up the code, it shows a misfire on cylinder 6 , so check the spark plug and and coil. If ther is no fault in the plug vor coil. start looking at the fuel injectors.

Thanks for the tip. I was going to start with the fuel injectors, perhaps pull them to have them tested/cleaned, but like your approach. I plan to connect with the shop that worked on the car last to see if they can tell me more about what work they did.

Update: pulled injectors and took to RC engineering for cleaning/calibration. Before: 2 dripping, 4 "good." After: 6 "excellent." Putting it back together this weekend. Changing spark plugs too. When pulling injectors, electrical plug on #6 cylinder (the offending, P0306) seemed a little loose. Will see what happens when it's all back together.

Final update: Boxster back together. Runs like new. Much stronger, smoother than before. Hope I never have to put those clips back on the injectors... That took forever. Have to take it by the shop to have CEL turned off. Will see if that was it. Test run had no blinking. My conclusion: Probably loose clip on electrical wire running to #6 cylinder. Came off too easy. Nevertheless, happy I had the injectors cleaned. Had work travel to LA that allowed me to drop-off/pick-up injectors in person. Nice folks at RC Engineering.