P1354: Ignition Coil C Primary Circuit Malfunction

P1354 flags a malfunction in the primary (low-voltage) circuit of ignition coil C. The PCM monitors current flow through each coil's primary winding every time it fires. When the signal on coil C falls outside the expected range -- whether that's no current, too much resistance, or an unexpected short -- the PCM logs P1354 and typically cuts fuel to that cylinder to protect the catalytic converter from unburnt fuel damage.

The primary circuit runs from the PCM's coil driver output, through the ignition coil connector, and through the primary winding inside the coil. A fault anywhere along that path will set this code. The most common causes are a failed ignition coil (internal winding breakdown), a damaged or corroded connector at the coil, a chafed or broken wire in the harness between the coil and PCM, or a failed coil driver circuit inside the PCM itself -- though PCM failure is the least likely scenario.

Start by swapping coil C with a known-good coil from another cylinder. If the fault code moves to that cylinder's code, the coil is the culprit. If P1354 remains on coil C after the swap, inspect the wiring harness and connector for corrosion or damage before considering the PCM. Given the High severity rating, don't delay on this one -- extended driving with an open ignition circuit accelerates catalytic converter wear.