P0356: Ignition Coil F Primary/Secondary Circuit Malfunction
Quick Answer
Not safe to drive
P0356 means the engine computer detected an electrical fault in the primary or secondary circuit of ignition coil F, the coil for cylinder 6 on engines with one coil per cylinder. It can only appear on engines with six or more cylinders, such as inline sixes, V6s and V8s. A failed coil is the usual cause, with a worn plug, a damaged connector or chafed wiring next in line.
- Severity
- Moderate · Ignition
- Estimated repair cost
- From €55 to €1500+, varies by vehicle
€55 or €1500, depending on your car.
- Replace ignition coil F (cylinder 6) only€55–€210
- Engine computer repair or replacement (failed coil driver, rare)€500–€1500
A scan shows whether P0356 is really stored on your car, which codes sit next to it and how urgent each one is. You can do this parked, with the ignition on.
A scan needs a Bluetooth OBD2 adapter (Bluetooth LE on iPhone), about €25-60; the built-in demo runs without one. See which adapter to buy
What does P0356 mean?
P0356 is a ignition-related diagnostic trouble code classified as moderate severity.
What are the symptoms of P0356?
- Check engine light on, usually with a cylinder 6 misfire code (P0306) stored as well
- Rough idle with a shake from the one cylinder that is not firing
- Hesitation and loss of power when accelerating
- Check engine light flashing under load while the misfire is active
- Fuel consumption up noticeably
- Raw fuel smell from the exhaust
- Occasional stall at idle or when coming to a stop
What causes P0356?
Failed ignition coil on cylinder 6 (open or shorted winding)
: high
Worn or fouled spark plug on cylinder 6 overstressing the coil
: high
Cracked coil boot or plug lead arcing to the cylinder head
: medium
Corroded, loose or oil-soaked connector on the cylinder 6 coil
: medium
Oil in the spark plug well from a leaking valve cover gasket
: medium
Chafed or heat-damaged wire between the engine computer and the coil
: low
Failed coil driver inside the engine computer
: low
Is it safe to drive with P0356?
No - address this immediately. You can limp to a workshop, but a coil that is not firing sends unburned fuel from cylinder 6 into the exhaust, where it overheats the catalytic converter. Get it fixed within a day or two, and if the check engine light flashes, stop driving.
How do you diagnose P0356?
- Read all stored codes and the freeze frame. A cylinder 6 misfire code (P0306) stored alongside P0356 confirms the cylinder is really dropping out, not just logging an electrical glitch.
- Find cylinder 6 in the service data for your engine. Coil F follows the engine's own cylinder numbering, and on V engines that numbering differs from maker to maker.
- Remove the cylinder 6 coil and inspect the boot for cracks, carbon tracks or oil, and the connector for green corrosion, bent or pushed-back pins and a broken locking tab.
- Swap the cylinder 6 coil with the one from cylinder 4, clear the codes and drive. If the fault moves (P0356 becomes P0354), the coil is bad. If P0356 returns, look at the plug, connector and wiring.
- Pull the cylinder 6 spark plug and check the gap, electrode wear and any oil or fuel fouling. A worn plug makes the coil work harder and can kill a new coil quickly.
- Key on, engine off: confirm battery voltage at the coil supply pin against a good ground. While cranking, check that the engine computer is switching the trigger wire with an LED test light or an oscilloscope. Avoid an ordinary bulb test light, which can load the trigger circuit on coils with a built-in igniter.
- Follow the harness towards the engine computer looking for chafing, heat damage or rodent bites, especially where it runs over the back of the engine or close to the exhaust.
- If coil, plug, supply and wiring all pass, the coil driver in the engine computer is the remaining suspect. That needs a workshop with an oscilloscope and the wiring diagram.
How much does P0356 cost to fix?
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace ignition coil F (cylinder 6) only | €25–€120 | €30–€90 | €55–€210 | Easy |
| Replace coil F plus the spark plug on cylinder 6 | €35–€150 | €40–€120 | €75–€270 | Easy |
| Full coil set and spark plug set (on a V8, eight of each) | €250–€900 | €120–€350 | €370–€1250 | Moderate |
| Repair coil connector pigtail or harness section | €10–€60 | €60–€180 | €70–€240 | Moderate |
| Valve cover gasket (oil in the plug wells), one cylinder head; V engines at the upper end | €60–€200 | €110–€600 | €170–€800 | Moderate |
| Engine computer repair or replacement (failed coil driver, rare) | €400–€1200 | €100–€300 | €500–€1500 | Professional |
Prices estimated as of October 2026. Costs vary by region, vehicle, and shop.
Full repair guides
P0356 on specific vehicles
P0356 on Chevrolet
Chevrolet Silverado 1500 5.3 V8 (Gen IV)
P0356 on BMW
BMW 5 Series 545i / 550i (N62 V8) · BMW X5 xDrive50i (N63 twin-turbo V8)
P0356 on Audi
Audi S5 Coupe (B8, 4.2 FSI V8)
Related diagnostic codes
Common questions about P0356
- Which cylinder does coil F fire?
- Coil F is the coil for cylinder 6 on engines with one coil per cylinder. On a lengthways-mounted inline six, such as the BMW ones, that is the rearmost cylinder next to the bulkhead. On V6 and V8 engines its position depends on how the maker numbers the banks, so check the service data or the diagram on the engine cover.
- Is P0356 the coil or the spark plug?
- The code points at the coil circuit, but a worn or fouled plug is a common reason a coil fails, because the coil has to produce a higher voltage to jump a wide gap. Check the plug whenever you replace the coil, or the new one can fail the same way.
- How do I test coil F without special tools?
- Swap the cylinder 6 coil with the one from cylinder 4, clear the codes and drive. If P0354 appears, the coil is faulty. If P0356 returns, the coil is fine and the plug, connector or wiring needs checking.
- Can I drive with P0356?
- Only to a workshop, and not if the check engine light is flashing. A dead coil means cylinder 6 is sending unburned fuel into the exhaust, which overheats the catalytic converter. Fix it within a day or two.
- My new coil failed within weeks. Why?
- Usually one of three things: a worn plug left in place, oil in the plug well from a leaking valve cover gasket, or a replacement coil that was faulty from new. Fix the underlying cause before fitting another coil.
Read our detailed guides
Sources
- en.wikipedia.org en.wikipedia.org/wiki/LS_based_GM_small-block_engine
- chevygeek.com chevygeek.com/ls-firing-order/
- apextechnation.com apextechnation.com/articles/gm-53-v8-common-problems
- en.wikipedia.org en.wikipedia.org/wiki/BMW_N62
- europremiumparts.com europremiumparts.com/blogs/bmw-buying-guides/bmw-n62-engine-guide-reliability-co
- companyofcars.com companyofcars.com/promotions/bmw-n62-n63-valve-stem-seal-repair/
- en.wikipedia.org en.wikipedia.org/wiki/BMW_N63
- alexsautohaus.com alexsautohaus.com/bmw-n63-common-problems/
- en.wikipedia.org en.wikipedia.org/wiki/Audi_S5
- 034motorsport.com 034motorsport.com/service/audi-volkswagen-carbon-cleaning-service-direct-injecte