P0351 - IGNITION COIL A PRIMARY / SECONDARY CIRCUIT MALFUNCTION

Modern vehicles use the Coil-In-Plug (COP) system. This system is based on a coil in each cylinder which is controlled by the Powertrain Control Module (PCM).

The coils have 2 wires: one is for battery power, and it is controlled by the power distribution center, while the other wire is from the coil activation circuit that comes from the PCM (Powertrain Control Module).

The Powertrain Control Module turns this circuit on or off to activate and deactivate the fuel pump.

The PCM constantly monitors the circuit of the coil controller, if you find faults in the circuit of coil number 1, for example, a short circuit, the DTC code P0351 OBDII is set. It should be mentioned that depending on the vehicle model, this code may be set by the fuel injector.

• Lighting malfunction (Check Engine).
• Power failures.
• Power loss.
• Unstable idling.

The reasons for setting the diagnostic code P0351 OBD2 are

• The cables and connectors leading to the ignition coil may be defective. They may have characteristics such as wear and tear or may rub against another component.
• A short in the ignition coil circuit.
• Defective ignition coil.

When faced with the fault code P0351 OBDII, you must do the following:

• If they fail at present, the problem may be intermittent. For that reason, move all the wires from the number 1 coil. If you do that and the fail remains, the problem is in the wires. Repair or replace as necessary.
• Verify that the electrical connection at the coil connector is not deficient.
• If the motor fault is present, turn the motor off and disconnect the wires related to coil number 1. Then, turn the motor on with the wires disconnected. By using a voltmeter on the AC Hertz scale, check the reading is between 5 and 20 Hz. If not present within this range, change the ignition coil.
• If there is no signal from the PCM to the ignition coil circuit, it is understood that the Powertrain Control Module (PCM) is connecting and disconnecting the circuit, leaving the coil disconnected and checking the DC voltage in the drive circuit at the ignition coil connector. If a significant voltage is present, it indicates a short circuit to voltage. You must locate it and make the necessary repair.
• If there is no voltage in the controller circuit, unplug the connector from the PCM and perform a controller continuity test between the Powertrain Control Module (PCM) and the coil. If there is no continuity, it means there is a short circuit to ground. Repair it.
• If continuity is present, verify the resistance between the ground and the ignition coil connector. The result should be infinite resistance. If not, repair the short to ground in the coil drive circuit.