P2300 means the Powertrain Control Module (PCM) has sensed a low‑voltage (ground) condition on the primary control circuit of an ignition coil, indicating the coil is not being driven properly. The fault is usually found in the coil itself, its wiring/connectors, or the ground path; the PCM rarely fails. When this code is set the engine typically runs rough or misfires and the Malfunction Indicator Lamp (MIL) illuminates.
An internally shorted coil will pull the primary circuit low, causing the PCM to set P2300. This is the most common cause, especially if the code appears after a single coil failure.
A chafed wire, pinched harness, or corroded terminal can short the primary circuit to ground or create an open, preventing proper voltage from reaching the coil.
If the ground reference for the coil driver is weak or missing, the circuit may read low even though the coil itself is functional.
The PCM’s internal output transistor that drives the coil can fail, resulting in a low‑side short. This is the least common cause and should be investigated only after ruling out the coil and wiring.
Insufficient voltage to the coil (e.g., from a weak ignition switch) can sometimes manifest as a low‑side fault, though the code specifically points to a ground‑side problem.
In the vast majority of cases the PCM is not the problem. The coil, its wiring, or a bad ground is the culprit. PCM replacement should only be considered after the coil and harness have been verified as good.
You may be able to drive short distances, but the misfire can damage the catalytic converter and worsen performance. It’s best to diagnose and repair the fault promptly.
Clearing the code without fixing the underlying issue will only cause the MIL to re‑illuminate once the PCM detects the fault again.
The generic definition refers to the coil designated 'A', which is typically the first cylinder (often cylinder #1). If your vehicle uses a coil‑per‑plug design, the fault applies to that specific coil.