P0625 indicates a low voltage condition in the generator (alternator) field circuit. The powertrain control module has detected that the voltage at the alternator’s field terminal is below the expected range.
A shorted or open field winding inside the alternator can prevent proper current flow, producing a low‑voltage reading.
Oxidation, broken pins, or a loose connection at the field terminal can cause intermittent or low voltage signals.
A blown fuse or open fusible link in the field circuit will cut power to the field coil, resulting in the low‑voltage condition.
Frayed, chafed, or shorted wires between the PCM and the alternator can drop voltage enough to trigger the code.
Very rarely, the PCM’s internal sensor that monitors field voltage can fail, but this is far less common than a component‑side problem.
It is possible but extremely unlikely. The PCM’s voltage sensor rarely fails; most cases are due to the alternator, its connector, fuse, or wiring.
Not necessarily. First verify the field circuit voltage and inspect connectors and fuses. If the alternator’s field winding is open or shorted, replacement is required; otherwise the issue may be a simple wiring or fuse problem.
Yes. With a low‑voltage field circuit the alternator cannot charge the battery properly, leading to a discharged battery and potential loss of vehicle operation.
That recommendation is a common misconception. In real‑world experience, the PCM is almost never at fault for this code; focusing on the alternator field circuit components resolves the problem in the overwhelming majority of cases.