The engine control module (ECM) has detected that the voltage in the primary control circuit for ignition coil H is lower than the expected threshold. This indicates an electrical fault, such as a short to ground, in the circuit that triggers the coil.
An internal short-circuit within the ignition coil H can cause the control voltage to drop below the detectable limit.
Frayed, pinched, or melted wires in the primary control circuit may be shorting to the engine block or chassis.
Corrosion or contamination in the coil connector pins can create high resistance or a bridge to ground.
A poorly seated connector at the coil or the wiring harness may cause an intermittent low-voltage signal.
An internal failure of the ignition coil driver circuit within the engine computer can cause an incorrect voltage reading.
No. This code refers specifically to the electrical control circuit of the ignition coil; it does not monitor the condition of the spark plug itself.
No. Replacing the PCM is rarely the correct first step. The vast majority of P2321 cases are caused by failed coils or damaged wiring.
Driving with a misfire can lead to catalyst damage due to unburned fuel entering the exhaust system. It is recommended to address the issue promptly.