P0350 Ignition Coil Primary/Secondary Circuit Malfunction
OBD-II Trouble Code Technical Description
Ignition Coil Primary/Secondary Circuit Malfunction
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles (Hyundai, Toyota, Chevy, Ford, Dodge, Chrysler, etc.). Although generic, the specific repair steps may vary depending on make/model.
If your OBD-II vehicle has stored a code P0350, it means that the powertrain control module (PCM) has detected a problem with the primary and/or secondary circuits for one or more ignition coils or ignition coil packs.
Most OBD-II equipped vehicles utilize a coil-over-plug, distributor less ignition system. In this type of system, each cylinder is outfitted with its own ignition coil which is attached to the spark plug using a short plug wire or silicon boot. Battery voltage, and a ground pulse from the PCM applied to a tightly wound induction coil, create the high-intensity spark (thousands of volts) that is required to fire the spark plug for each cylinder.
Systems which use coil packs function in a similar manner, except multiple spark plugs are fired from a coil pack which fires multiple cylinders in sequential order. This type of system typically uses longer high tension spark plug leads to transfer the high-intensity spark from the coil pack towers to the spark plugs.
Regardless of the type of ignition system with which the vehicle in question is equipped, spark timing and function are controlled by the PCM. Provided with a constant supply of switched battery voltage (with the ignition switch on), the ignition coil releases a high-intensity spark when it receives a ground pulse from the PCM.
If the PCM detects that any of the ignition coil circuits are not being completed when the ground pulse is applied, a code P0350 will be stored and a malfunction indicator lamp (MIL) may be illuminated.
Code Severity & Symptoms
Ignition misfire issues will likely accompany a code P0350; therefore it should be categorized as severe.
Symptoms of this code may include:
Drivability issues, including one or more ignition misfires Poor engine performance Diminished fuel efficiency Cylinder misfire codes will likely accompany a code P0350 (e.g. P0301, P0302, P0303, P0304, etc.)Causes
Potential causes for this code to set are:
Open or shorted primary/secondary circuits Defective ignition coils or coil pack/s Bad ignition system relay Blown fuses or fusible links Faulty PCM or a PCM programming errorDiagnostic and Repair Procedures
In order to diagnose a code P0350, I would need a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source, such as ALL DATA (DIY).
A visual inspection of all ignition coil/pack wiring and connectors is the best place to begin your diagnosis of a code P0350. Be on the lookout for broken electrical connectors at the ignition coils or coil packs. Also check for wiring that is burned, broken, or corroded. I have personally found rodent damaged wiring to be the cause of a code P0350 in several customer cars. Ignition coil electrical connector ends are also known for becoming corroded over time.
I would continue by connecting the scanner to the vehicle diagnostic port and retrieving all the stored codes and freeze frame data. I have found it helpful to record this information for later. Next, I’d clear the codes and test-drive the vehicle to see if the P0350 is reset.
Use your vehicle information source to search technical service bulletins (TSB) that may help with your diagnosis. TSBs with matching symptoms and codes can prove very helpful if you use the diagnostic tips found therein.
If there are cylinder specific ignition coil primary /secondary circuit codes present, they may
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