What Does P0356 Mean?
The ECM has detected a primary or secondary circuit malfunction in ignition coil F, typically serving cylinder #6. The coil's electrical behavior during commanded firing events is outside expected parameters, indicating the coil cannot properly generate the high-voltage spark needed for combustion. On V6 engines this is the last cylinder, and failure creates a noticeable balance issue and rough running condition.
Common Causes
40%
Failed ignition coil F with cracked housing or internal winding breakdown from thermal stress and age
25%
Open, short, or high-resistance wiring in the coil F control circuit between ECM and coil connector
20%
Worn spark plug on cylinder 6 with excessive gap or damaged electrode requiring more voltage than the coil can deliver
15%
ECM internal ignition driver transistor failure for the cylinder 6 output channel
Diagnostic Steps
1
Perform a coil swap test between coil F and a known-good coil from another cylinder. Clear codes, run the engine, and note whether the code follows the coil or stays at the same cylinder position.
2
Measure coil F primary and secondary winding resistances and compare to specification. Check the coil boot for tears, carbon tracking, or degraded spring contact.
3
Inspect the coil F power supply and trigger signal connectors for heat damage, corrosion, or terminal push-back. On V6 engines, cylinder 6 is often in a high-heat area.
4
Verify 12V power at the coil F connector and proper ECM trigger signal during cranking using a digital multimeter or oscilloscope.
5
Remove and inspect the cylinder 6 spark plug. Replace if gap exceeds spec or if insulator shows signs of detonation damage (white, blistered, or eroded).
Estimated Repair Cost
$60 - $300
Parts + labor, varies by vehicle and location
The ECM has detected a primary or secondary circuit malfunction in ignition coil F, typically serving cylinder #6. The coil's electrical behavior during commanded firing events is outside expected parameters, indicating the coil cannot properly generate the high-voltage spark needed for combustion. ...
The most common cause of P0356 (Ignition Coil F Primary/Secondary Circuit Malfunction) is: Failed ignition coil F with cracked housing or internal winding breakdown from thermal stress and age
Typical repair costs for P0356 range from $60 to $300, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Ignition coil F failure causes continuous cylinder 6 misfire, reducing engine power and efficiency. The unburned fuel entering the exhaust system can overheat and damage the catalytic converter if driving continues.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0356 to identify the root cause.
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Quick Info
Category
Powertrain
System
Ignition System
Difficulty
Type
Generic (SAE)
Recommended Tools
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