I have a 96 Ford Explorer with a 6 cyl. 4 L engine. I have a had a problem with the check engine light. My code scanner indicates P0401 and P0402 codes. I checked the EGR valve and took it off to clean it, appears OK. It will hold 5 in. of vacuum. I checked the vacuum from the engine to the EGR vacuum regulator. I get 22 in of vacuum to the regulator but nothing after the regulator. I replaced the EGR vacuum regulator but still get the P0401 code. I check the harness side of the EGR vacuum regulator with the switch on (engine not running) and get 11.5 volts, not the 4-6 v indicated in the manual. I also checked the harness side of the DFPE sensor and get 5 volts running cold, not the .35-.8 volts indicated in the manual. Is this a problem with the DFPE or PCM or something else?