Faulty ignition coil 'F' (primary or secondary winding failure); Worn or damaged spark plug or spark plug boot; Damaged wiring or connector at the ignition coil 'F'; Open or short circuit in the coil control circuit between the ECM and coil 'F'; Corroded or loose ground connection for the ignition coil; Failed driver circuit inside the ECM (less common)

DTC codes / P03xx · Ignition system and misfire / P0356

P0356Ignition Coil 'F' Primary/Secondary Circuit

Q: What does code P0356 mean?

Ignition Coil 'F' Primary/Secondary Circuit. P0356 indicates that the engine control module (ECM) has detected a fault in the primary or secondary circuit of ignition coil 'F', which is usually the coil for a specific cylinder. The ECM monitors the coil's electrical behavior and sets this code when the circuit does not respond as expected during engine operation.

P0356 indicates that the engine control module (ECM) has detected a fault in the primary or secondary circuit of ignition coil 'F', which is usually the coil for a specific cylinder. The ECM 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
Engine misfire, especially under load or acceleration
Rough idle or shaking felt through the steering wheel and seats
Reduced engine power or sluggish acceleration
Poor fuel economy due to incomplete combustion
In some cases, a flashing check engine light indicating a severe misfire that can damage the catalytic converter

Common causes, most likely first

Faulty ignition coil 'F' (primary or secondary winding failure)
Worn or damaged spark plug or spark plug boot
Damaged wiring or connector at the ignition coil 'F'
Open or short circuit in the coil control circuit between the ECM and coil 'F'
Corroded or loose ground connection for the ignition coil
Failed driver circuit inside the ECM (less common)

How to diagnose and fix it

Perform a visual inspection of the ignition coil 'F', its connector, and wiring for damage or corrosion
Swap ignition coil 'F' with a known-good coil from another cylinder to see if the misfire follows the coil
Test the primary and secondary resistance of the coil with a multimeter and compare to specifications
Check for spark at the affected cylinder using a spark tester
Inspect and test the spark plug and replace if worn or fouled
Check the coil control circuit for continuity and shorts between the ECM and coil 'F'
If all else checks out, test the ECM driver circuit or consult a professional for advanced diagnostics

Ignition coil 'F' circuit pitfalls

A P0356 code can be set by a faulty spark plug or boot that causes the coil to work harder and eventually fail, so always inspect the plug when replacing a coil.
The coil 'F' designation does not always correspond to cylinder 6; always consult the vehicle's specific coil identification chart to avoid replacing the wrong coil.
Intermittent wiring issues, such as a chafed wire that only shorts when the engine moves, can set this code without a hard failure, so wiggle-test the harness while the engine runs.
A weak battery or charging system problem can cause low voltage to the coils and trigger a P0356 code, so check battery and alternator output before condemning the coil.
After replacing the coil, the code may remain stored until the ECM completes a successful drive cycle, so clear the code and verify the repair with a test drive.

Can I keep driving with P0356?

It is not recommended to drive for extended periods with a P0356 code, especially if the check engine light is flashing, as continued misfiring can damage the catalytic converter and cause poor performance. Limit driving to a short distance to a repair shop or until the fault is diagnosed.

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.