'99 Ranger flex fuel 3 liter engine. I was getting a check engine light on the instrument panel. Went to AutoZone and got my codes scanned, P0402 (Exhaust Gas Recirculation Flow Excessive Detected) showed up. Removed the EGR module and checked the diaphragm, no problem. Before removing the EGR valve I had disconnected the negative side of the battery. Anyway, after reinstalling the EGR valve I reconnected the negative cable to the battery and started the engine. The check engine light went off. Ok, I thought the situation was fixed.
However, about 6 weeks later the check engine light comes on again. This time I didn't mess with the EGR valve, I just disconnected the negative cable and then reconnected it. Again, no check engine light. Question, any guesses as to what is going on? Is it likely that the check engine light will come on again? Anyone else with this problem? How did you fix it? I'm not a mechanic by trade. Any suggestions? Thanks, Lee