Circuit description

Direct ignition system (S-TDI) is used in this vehicle. In addition to ever precise ignition, S-TDI controls a loss under high voltage condition to improve overall reliability of the ignition system. The S-TDI uses one ignition coil per cylinder for ignition. The engine control computer determines ignition timing and outputs ignition signal (IGT) to individual cylinders. In response to the IGT signal, the ignition drive IC inside the igniter cuts an electric current to the primary coils in the ignition coil. This generates the counter-electromotive force in the secondary coils and ignites the spark plugs.

Fig 1: Ignition Coil System Diagram

Courtesy of SUBARU OF AMERICA, INC.

DTC DETECTION CONDITION

DTC No.	DTC detection conditions	Suspected parts
P0351	The ECM driver IC detects the open or short circuit between No. 1 ignition coil and ECM (open circuit detection/GND short/+B short). (1 trips detection logic)	Ignition system Open/short condition in the IGN circuit (1 to 4) between the ignition coil and ECM. Ignition coil (Cylinders No. 1 to 4) ECM
P0352	The ECM driver IC detects the open or short circuit between No. 2 ignition coil and ECM (open circuit detection/GND short/+B short). (1 trips detection logic)
P0353	The ECM driver IC detects the open or short circuit between No. 3 ignition coil and ECM (open circuit detection/GND short/+B short). (1 trips detection logic)
P0354	The ECM driver IC detects the open or short circuit between No. 4 ignition coil and ECM (open circuit detection/GND short/+B short). (1 trips detection logic)