P0356
Ignition Coil F Primary/Secondary Circuit Malfunction
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The P0356 code indicates a malfunction in the circuit of Ignition Coil F, responsible for firing cylinder 6. This code appears on engines with 6 or more cylinders. On a V6, cylinder 6 is typically the rearmost cylinder on one bank, while on V8 engines it may be mid-bank depending on the manufacturer's firing order.
The diagnostic and repair process is the same as other ignition coil codes. The coil swap test remains the gold standard: swap the cylinder 6 coil with another cylinder, clear codes, and run the engine to see if the code follows the coil. If it does, the coil is bad. If it stays on cylinder 6, check the wiring, connector, and PCM driver.
On V6 engines where cylinder 6 is at the back of the engine near the firewall, access can be challenging. Some vehicles require removal of the upper intake plenum to reach the rear coils. This is why professional labor costs are slightly higher for these cylinders. If you're tackling it yourself, take photos before disassembly and label any vacuum hoses or connectors you remove. Replace the spark plug at the same time — it's false economy to put a new coil on an old plug.
Severity
Symptoms
- •Engine misfires or runs rough
- •Check Engine light is on (may flash)
- •Rough idle with vibration
- •Loss of power on acceleration
- •Unburned fuel smell from exhaust
- •Decreased fuel economy
Likely Causes
The ignition coil for cylinder 6 has failed internally, unable to generate the high voltage needed to fire the spark plug.
Heat, vibration, or corrosion has damaged the wiring or connector to the cylinder 6 ignition coil, interrupting the PCM's control signal.
A degraded spark plug on cylinder 6 increases voltage demand beyond the coil's capability, eventually causing coil failure.
The PCM's internal driver for the cylinder 6 coil has malfunctioned, preventing proper coil activation and deactivation.
An issue with the shared power feed or ground circuit for the ignition coils is preventing proper operation of the cylinder 6 coil.
Estimated Cost
Professional Repair
Includes parts + labor
Common Fixes
- Replace the ignition coil for cylinder 6
- Replace the spark plug for cylinder 6
- Repair or replace damaged wiring and connectors
- Swap the coil with another cylinder to verify the fault
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Causes and Fixes P0356 Code: Ignition Coil F Primary / Secondary Circuit Malfunction
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