Faulty ignition coil D, often due to internal winding failure or insulation breakdown; Worn or damaged spark plug or spark plug boot on the affected cylinder; Corroded, loose, or damaged electrical connector at the coil; Open or shorted wiring in the coil primary circuit, including chafed harnesses; Failed ignition control module or driver circuit inside the engine control module; Poor engine ground or faulty power supply to the coil; Oil or moisture contamination in the spark plug well shorting the coil

DTC codes / P03xx · Ignition system and misfire / P0354

P0354Ignition Coil D Primary/Secondary Circuit Malfunction

Q: What does code P0354 mean?

Ignition Coil D Primary/Secondary Circuit Malfunction. P0354 indicates that the engine control module has detected an abnormal condition in the primary or secondary circuit of ignition coil D, which is the fourth coil in the firing order on most engines. The computer monitors the coil's electrical behavior and sets this code when the circuit does not respond as expected during engine operation.

P0354 indicates that the engine control module has detected an abnormal condition in the primary or secondary circuit of ignition coil D, which is the fourth coil in the firing order on most engines. The computer monitors the coil's electrical behavior and sets this code when the circuit does not respond as expected during engine operation.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Rough idle or misfire sensation, especially when the engine is cold or under load
Loss of power or hesitation during acceleration
Shaking or vibration from the engine bay that may feel like a dead cylinder
Worse fuel economy than usual due to incomplete combustion
In some cases, a flashing check engine light if the misfire is severe enough to damage the catalytic converter

Common causes, most likely first

Faulty ignition coil D, often due to internal winding failure or insulation breakdown
Worn or damaged spark plug or spark plug boot on the affected cylinder
Corroded, loose, or damaged electrical connector at the coil
Open or shorted wiring in the coil primary circuit, including chafed harnesses
Failed ignition control module or driver circuit inside the engine control module
Poor engine ground or faulty power supply to the coil
Oil or moisture contamination in the spark plug well shorting the coil

How to diagnose and fix it

Perform a visual inspection of coil D, its connector, and the spark plug well for damage, corrosion, or contamination
Swap coil D with a known-good coil from another cylinder and see if the misfire code follows the coil
Test the spark plug and replace it if worn, fouled, or damaged
Use a multimeter to check the primary and secondary resistance of the coil and compare to specifications
Inspect the wiring harness for opens, shorts, or poor connections between the coil and the engine control module
Check for power and ground at the coil connector with the key on and during cranking
If all external components test good, diagnose the engine control module driver circuit or replace the module as needed

What the code does not always mean

A P0354 code does not automatically condemn the ignition coil; a faulty spark plug or plug boot can cause the same circuit fault by forcing the coil to work harder.
Swapping coils between cylinders is the fastest way to confirm whether the coil itself is at fault, but the code may not follow if the problem is in the wiring or the control module.
Corrosion inside the coil connector is a frequent hidden cause, especially on engines where the coil sits in a deep well that collects water or oil.
Some vehicles set P0354 when the ignition coil driver inside the engine control module fails, which means replacing the coil will not fix the problem.
A misfire severe enough to flash the check engine light can quickly overheat the catalytic converter, so driving with P0354 should be limited until diagnosed.

Can I keep driving with P0354?

It is generally safe to drive a short distance to a repair shop if the check engine light is steady and the engine runs smoothly, but avoid heavy acceleration or towing. If the check engine light flashes or the engine runs very rough, stop driving to prevent catalytic converter damage.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.