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Hello. I need help please. I have 2006 Ford Explorer 6 cylinder 4.0L that l just replaced the Fuel Pump (complete with strainer, sensors, etc) and the fuel pump then had to replace fuel lines because someone cut one, no leaks anywhere and won't fire now. Plugged in computer and got this code P0642, then cleaned out 2 bird nests, 1 in air intake (which l got cleaned out) and the other in the valley right below the intake manifold cover (where l pulled 3 live naked babies out of then vacuumed out). Could those nests have caused that code to come up or something from changing the fuel pump? Please help
P0642 is defined as "Sensor Reference Voltage A Circuit Low". Because the code was there after the fuel pump replacement, but before you went cleaning out nests, I'm gonna take a WAG that the Fuel Tank Pressure sensor has something to do with it.
Start out with confirming that the reference circuit is low. Key on, unplug the A/C pressure sensor and check all three pins for voltage with a multimeter connected to B-. The A/C pressure sensor lives in the drivers front of the engine bay, by the battery: