PCM Power Input Intermittent
The engine computer is not getting steady power. This can happen because the power relay is failing, there is a wiring problem, or the PCM itself has an internal fault. When the PCM loses power, the engine may run poorly, stall, or not start.
You may be able to drive a short distance if the engine runs normally, but the fault can cause sudden stalling or no-start conditions. Do not drive if the vehicle is shutting off, hesitating badly, or showing multiple electrical problems.
P2509 indicates an intermittent loss of battery voltage, ignition feed, or relay-controlled power to the powertrain control module. The PCM monitors its own power supply and sets this code when the voltage drops out unexpectedly or for too long. The problem is commonly caused by a bad PCM power relay, poor connections, damaged wiring, blown fuse, or less commonly an internal PCM fault.
Yes. A failing PCM power relay is one of the most common causes of P2509.
Yes. If the PCM loses power long enough, the engine may not start or may stall.
Yes. Weak battery voltage or charging system problems can interrupt PCM power and set this code.
No. External power, ground, relay, fuse, and wiring checks should be done first.