ECU "Doesn't remember codes"?

[xclusivecar]

I have had 3 instances in the past week of the Boxster running extremely rough at startup and the CEL flashing. After turning off the car and waiting 1/2 hour I can turn the car back on and the CEL is now solid. 3 Hours later and the CEL does not light up at all. I took the car to the dealership and after supposedly hooking the car up to get the codes they call me and say "no codes are available! The car is just fine!"

Does the ECU just "dump" codes from memory when the CEL goes out? As far as I knew all codes are retained until flushed out by an OBDII computer. Anyone have extensive knowledge of how the ECU in our cars works? Now im thinking of getting my own little OBDII device to check things myself before bringing the car in for service so they cannot blatently lie to me! Sorry so long...had to vent! :cursing:

Paul

[Tool Pants]

If whatever fault code set off the light is not detected again then after a number of start/drive cycles the code is deleted.

There is no 'delete all old codes' function on a PST2. They go away by themselves from the DME if not detected again under the parameters that set if off.

[xclusivecar]

That stinks! The car was not able to be driven while in the condition it was in. When I finally could drive it to the dealership the car acted fine and I wish they could pull a code to see what had gone wrong. As we all know, the car will start acting bad once I get it back home! :P Well I guess it would be a good idea to buy an OBDII scan tool to get the codes as it is happening. Thanks for the replies!

Paul

[Loren]

A scan tool can't pull codes that are not there anymore. You would need to get a recording tool that catches all codes and then later you dump the codes into a computer. I think Autozone sells one but I can't remember the brand name - maybe Datalogger or something like that.