P2407 means the powertrain control module has detected an intermittent or erratic voltage signal from the evaporative emission (EVAP) leak detection pump (LDP) sense circuit. The sense circuit tells the PCM whether the EVAP system is holding vacuum during a self-test, so an unstable signal prevents the leak test from completing reliably.
The internal changeover switch or motor wears out, producing dropouts or unstable voltage on the sense line. This is the single most common cause of an erratic LDP signal.
Moisture and oxidation at the pump's connector create an unstable connection. Unplugging, inspecting, and reseating the connector often restores proper signal.
Chafed insulation, broken wires inside the insulation, or a stretched harness near engine mounts can cause intermittent opens or shorts to ground that the PCM reads as an erratic signal.
A hose that is not fully seated, cracked at a bend, or installed on the wrong port can keep the LDP from pulling a stable vacuum, indirectly causing the sense circuit to behave erratically.
A corroded or loose ground splice shared with the LDP can produce fluctuating reference voltage. Ground issues are less frequent than pump or connector failures but should be checked.
Genuine PCM failures that specifically produce an erratic LDP sense reading are rare. The PCM should only be considered after the pump, connector, harness, and grounds have all been tested and ruled out.
It is not a safety or drivability issue. The fault only affects the EVAP system's ability to self-test for fuel-vapor leaks, but the check engine light will stay on and the vehicle will not pass an emissions inspection until it is repaired.
Yes. The vehicle is generally safe to drive normally. The system in question is for controlling fuel vapor emissions, not for engine operation or braking.
Almost never. Although some online guidance suggests replacing the powertrain control module for this code, the leak detection pump, its connector, and its wiring are the actual cause in the vast majority of cases. The PCM should only be suspected after the pump and the entire harness have been electrically tested and ruled out.