Code P2402 Revisited
 

This 2006 Mazda 6 has about 55,000 miles, 4cyl engine (not speed), manual trans. In August the CEL came on. Asked questions here, got a new gas cap. Eventually got a code reader and have been watching. Just waiting for the CEL can be deceiving.
If I drive for awhile, get out and immediately open the gas cap for any reason or no reason if you will, the P2402 PB code is set when the engine comes on next. The CEL does not light. The next time the car is started (just starting several times does not do this have to drive some each time) the P2402 code is set and the CEL comes on (maybe have to wait for the third startup, sometimes not).
If I erase the error code at this point the PB2402 code is NOT set anytime after that until its time to open the gas cap again.
If we stop for gas, go to the bathroom and then come out to open the gas cap the code is NOT set and the CEL does not come on that cycle. I read that this probably avoids interupting the evap pump's operations by opening the cap to release pressure etc.
Of course these events did not happen for the first 50,000 miles or so.

I realize the pump and some parts are available from a port under the back seat. I assume some sensor in there has failed but the entire unit will end up being replaced. Looking for suggestions before I go in and face the fact that this will cost $500. Thanks.

There is a tsb on that problem and the pump will most likely have to be replaced. It will not effect driveability but will not pass state inspection if you are in an area that requires it. Unless you clear the code and get an inspection before the light comes back on of course.

I'm not able to locate a tech bulletin on this particular issue. I think I 'm going to have to go into service loaded for bear. If you can point me in the right direction would very much appreciate it. Thanks.