I have a 98 Maxima GLE w/federal emissions and 115K miles.

Does anyone know anything about MIL code 0312 (P1493)? The Haynes manual says: "EVAP canister purge control valve solenoid valve or circuit fault".

I have replaced the following valves in the engine compartment and still get the same MIL code after a few days:
* EVAP canister purge control valve
* EVAP canister purge cut valve
* EVAP canister purge cut solenoid valve

The PCM was also changed but after a few days the MIL with 0312 code came back again.

Could the problem be the canister vent control valve or the canister or both. I see where this is a common problem with Maximas of this era. The vent control valve was already replaced once, about 3 years ago. But, if this is the problem, why wouldn't I get the same MIL code 0903 (P0446) that I got before?

Finally, can anyone send me a diagram identifying all of the different valves located around the vapor canister? The vent control valve is attached to the canister, but there are four or five others in the area with vacuum and/or fuel lines that seem to be associated with the canister.

One final clue: the car was stalled in high water (high enough to get inside the car when the front door was opened; that's why the PCM was replaced) for a few minutes until it was pushed out. The 0312 code didn't appear immediately after the car was restarted (instead about a week or two later), so it may not even be related to the high water. And the 0312 code showed up before and after the PCM was replaced, so that replacement probably wasn't needed. 0312 is the only error code that has showed up following the high water incident (it's been about 8 weeks now).

Thanks for the help,
Jack