The P0622 code indicates that the engine control module (PCM) has detected a circuit malfunction in the alternator field terminal. This typically means the computer cannot properly regulate the alternator's voltage output due to an electrical open or short in the field circuit.
Internal failure of the alternator's field windings or the internal voltage regulator.
Frayed, broken, or shorted wires in the field terminal circuit between the PCM and the alternator.
Corrosion or loose pins at the alternator plug or the PCM harness causing high resistance.
A blown fuse in the charging system circuit that interrupts power to the field terminal.
A failure in the PCM's internal driver circuit that controls the field terminal current.
Not necessarily, although it is the most common cause. Wiring damage or a blown fuse can trigger the same code.
It is risky; if the alternator is not charging the battery, the vehicle will eventually lose all electrical power and stall.
No. PCM failure is rare for this circuit. Always exhaustively test the alternator and the wiring harness before considering a computer replacement.