2002 Ford Explorer XLT V6 4.0L P0231 Fuel Pump Secondary Circuit Low Code Diagnosis
I own a 2002 Ford Explorer XLT with a 4.0L V6 engine. Approximately two to three months ago, after replacing the fuel pump, my "Service Engine Soon" light activated. The check engine light triggered two diagnostic codes: P0455 and P0231. I resolved the P0455 issue, but am still unable to identify the root cause of the P0231 code. The P0231 code indicates a "Fuel Pump Secondary Circuit Low" fault. Possible causes include: a blown fuel pump fuse, an open circuit in the fuel pump monitor signal path, or a faulty fuel pump relay. I have already replaced the fuel pump relay and confirmed that the fuel pump fuse is intact. The vehicle starts normally, runs smoothly, and has not experienced any stalling or shutdowns. I'm now looking for further troubleshooting steps to resolve this issue. Any insights into potential wiring issues or sensor feedback problems would be greatly appreciated.
If the fuel pump is functioning properly, the fault likely lies in the monitor circuit. As noted on this forum: "Suspect an open in the feedback circuit between the Powertrain Control Module (PCM) and where it splices into the fuel pump supply voltage circuit."