P0357: Ignition Coil G Primary/Secondary Circuit Malfunction
Quick Answer
Not safe to drive
P0357 means the engine computer saw an electrical fault in the primary or secondary circuit of ignition coil G, the coil for cylinder 7. Because it needs at least seven cylinders, the code appears on V8, V10 and V12 engines. The coil itself is the most common cause, followed by a worn plug, a damaged connector or boot, and wiring faults.
- Severity
- Moderate · Ignition
- Estimated repair cost
- From €55 to €1500+, varies by vehicle
€55 or €1500, depending on your car.
- Replace ignition coil G (cylinder 7) only€55–€210
- Engine computer repair or replacement (failed coil driver, rare)€500–€1500
A scan shows whether P0357 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 P0357 mean?
P0357 is a ignition-related diagnostic trouble code classified as moderate severity.
What are the symptoms of P0357?
- Check engine light on, usually with a cylinder 7 misfire code (P0307) 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
- Popping or backfiring from the exhaust under hard throttle
What causes P0357?
Failed ignition coil on cylinder 7 (open or shorted winding)
: high
Worn or fouled spark plug on cylinder 7 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 7 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 P0357?
No - address this immediately. You can limp to a workshop, but a coil that is not firing sends unburned fuel from cylinder 7 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 P0357?
- Read all stored codes and the freeze frame. A cylinder 7 misfire code (P0307) stored alongside P0357 confirms the cylinder is really dropping out, not just logging an electrical glitch.
- Find cylinder 7 in the service data for your engine. Coil G follows the engine's own cylinder numbering, and on V engines that numbering differs from maker to maker.
- Remove the cylinder 7 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 7 coil with the one from cylinder 5, clear the codes and drive. If the fault moves (P0357 becomes P0355), the coil is bad. If P0357 returns, look at the plug, connector and wiring.
- Pull the cylinder 7 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 P0357 cost to fix?
| Repair | Parts Cost | Labor Cost | Total Estimate | DIY Difficulty |
|---|---|---|---|---|
| Replace ignition coil G (cylinder 7) only | €25–€120 | €30–€90 | €55–€210 | Easy |
| Replace coil G plus the spark plug on cylinder 7 | €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 on one bank of a V8 (oil in the plug wells) | €60–€200 | €440–€600 | €500–€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
P0357 on specific vehicles
P0357 on Chevrolet
Chevrolet Silverado 1500 5.3 V8 (Gen IV)
P0357 on BMW
BMW 5 Series 545i / 550i (N62 V8) · BMW X5 xDrive50i (N63 twin-turbo V8)
P0357 on Audi
Audi S5 Coupe (B8, 4.2 FSI V8)
Related diagnostic codes
Common questions about P0357
- Which cylinder is coil G on a V8?
- Coil G is the coil for cylinder 7. On GM V8s that is the rearmost cylinder on the left bank; on Ford V8s it is the third cylinder back on the left. European makers use their own numbering, so confirm it in the service data before you start.
- Why does P0357 come with P0307?
- P0307 is the misfire the engine computer measures on cylinder 7, and P0357 is the electrical fault in the coil that caused it. When both are stored together, the ignition side is almost certainly the place to look.
- Can I test the coil myself?
- Yes. Swap the cylinder 7 coil with the one from cylinder 5, clear the codes and drive. If P0355 appears, the coil is bad. If P0357 comes back, check the plug, the connector and the wiring to that coil.
- How long does it take to change a rear coil on a V8?
- Where the coils sit on top of the engine it can take a few minutes. On some V8s the rear coils sit under intake parts or covers, and the job can take an hour or more, which is why replacing the whole set in one visit is sometimes cheaper overall.
- Will P0357 fail a roadworthiness test?
- It can. Inspection rules are set nationally and vary by country, but a lit check engine light or a stored emissions-related fault can get a car rejected at the emissions part of the test, and a misfiring cylinder can push exhaust readings out of range. Clearing the code just before the test does not help, because the readiness monitors will show as not complete.
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