P0357 code: Ignition Coil G Primary/Secondary Circuit (Cylinder 7)
P0357 means ignition Coil G Primary/Secondary Circuit (Cylinder 7). The code says where to look, not what failed — the fix depends on which cause your car actually has.
What P0357 means
Coil G is the ignition coil for cylinder 7, so this code only shows up on engines with at least seven cylinders — in practice, V8s and larger. The ECM switches each coil's primary circuit to trigger the spark and verifies the circuit electrically on every firing event; P0357 means coil G's circuit read as open or shorted. This is an electrical failure, distinct from a worn spark plug: the plug can be brand new and this code will still set if the coil windings, connector, or wiring have failed. The likely causes, in rough order: a failed coil, an unplugged or corroded connector, chafed harness wiring on that bank, a blown fuse in the coil feed, and — rarely — the coil driver inside the ECM. With no spark reaching cylinder 7, the companion misfire code P0307 typically sets too, and you'll feel the missing cylinder as a rhythmic roughness, though a V8 can mask a single dead hole better than a four-cylinder can.
P0357 symptoms
- Misfire on cylinder 7 — uneven idle, subtle rhythmic shake
- Reduced power, most obvious under hard acceleration or towing
- Check-engine light, flashing while misfiring
- Fuel smell at the exhaust
- Companion misfire code P0307 usually present
What it costs to fix P0357
Typical range: $60–$450 · about ~0.2–2 hrs of labor
| If the cause is… | Part | Labor |
|---|---|---|
| Ignition coil (single) | $30–$150 | ~0.2–1 hrs |
| Wiring or connector repair | $5–$50 | ~0.5–2 hrs |
| Spark plugs (while in there) | $20–$100 | ~0.5–1.5 hrs |
Most V8 coils sit on top of the valve covers and swap out quickly, so this is usually a low-labor job. The exceptions are engines where rear cylinders tuck under cowling or intake plumbing, and tight engine bays where reaching cylinder 7 takes patience — wiring faults also add diagnostic time that a simple coil swap doesn't.
The price swings on which cause it turns out to be — so confirm the cause before paying. Diagnose P0357 for my exact vehicle →
How to fix P0357
Easy — basic tools, most owners can do this
- Confirm where coil G sits on your V8
Coil G fires cylinder 7, which needs at least seven cylinders — almost always a V8. Which bank it's on depends on the maker's numbering, so check the diagram, and note whether your engine mounts coils directly on the plugs or on the valve cover with short plug wires.
- Test output with an adjustable spark tester
Connect a spark tester between coil G's output and ground and crank or idle the engine. A strong, regular blue spark across the gap shows the coil is producing output; a weak, orange, or missing spark compared with a healthy cylinder on the same engine points to the coil or its supply.
- Inspect the boot or lead for heat and tracking
Look for a cracked boot, a burned spot, or a thin carbon line where spark has been escaping. Where short wires join coils to the plugs, check the cylinder 7 lead where it passes the exhaust manifold — heat-cooked insulation leaks spark. Replace the damaged piece and put a little dielectric grease inside the new boot.
- Swap coil G across to the other bank
Fit coil 7 on a cylinder across the engine, give it a few minutes of mixed driving, and rescan. If the circuit fault now names the other cylinder's coil letter, buy one coil; if it still reads coil G, follow that bank's harness from the connector toward the ECM for rubbed or pinched spots.
- Probe feed and trigger before blaming the ECM
With the coil unplugged, confirm battery voltage on the feed and a good ground, then check the trigger wire for an open or a short to ground between the connector and the ECM pin using the wiring diagram. Only when that wire tests clean and a good coil still won't clear the code does the ECM's driver for cylinder 7 come into question.
DIY or shop? On pickups and rear-drive V8s with coils on top of the valve covers, this is a straightforward driveway job: inspect, swap, replace. The spark tester and meter checks are entry-level. It turns into a shop job when the coil hides under intake or accessory brackets on a tightly packed engine, when the fault lives in the harness between the coil and the computer, or when an ECM driver is suspected — module replacement typically needs programming.
Tools for the DIY steps: OBD-II scanner · Adjustable spark tester · Digital multimeter · Dielectric grease · Socket set and extensions
Not sure which step applies to your car? Get the likely cause for your exact vehicle before buying anything for P0357.
Start a case with P0357 and your car. Redline weighs these causes against what your car shows, and names the check that would settle it before you buy parts.
Can I drive with P0357?
Redline can’t determine from a symptom or code alone whether your car is safe to drive.
P0357: common questions
Does P0357 only apply to V8 engines?
It requires an engine with at least seven cylinders, so in practice you'll see it on V8s, V10s, and V12s. If a scan tool reports P0357 on a four- or six-cylinder engine, doubt the scan before doubting the car — that combination shouldn't exist.
Coil or plug — which one is P0357 blaming?
The coil circuit. This code sets when the electrical path through coil G is open or shorted, which a worn spark plug can't cause. Replace or swap-test the coil and inspect its connector and wiring; do the plug too if it's due, but the plug isn't the trigger.
How much will P0357 cost to fix?
Commonly modest — one coil plus a short labor stint, since most V8 coils are top-of-engine. A wiring repair is cheap in parts but adds diagnostic time. The expensive outcome isn't this repair; it's the catalytic converter you can damage by driving on the misfire too long.
Is it OK to drive my truck with P0357 while towing?
Skip the towing until it's fixed. Heavy load is exactly when a misfire dumps the most unburned fuel into the catalyst and when the engine most misses that cylinder. Whether the truck should be driven at all is more than the code can say — get it repaired promptly, and stop driving if the light flashes.
Related trouble codes
Don’t have a scanner yet? A ~$25 Bluetooth adapter reads codes like P0357 from your phone. See our guide to the best OBD2 Bluetooth adapters. Run a repair shop? See Redline for shops.
Generic OBD-II reference. Manufacturer-specific behavior varies. Confirm with a scan tool and, for safety-related codes, a professional inspection. Cost ranges are reference ranges, not quotes.
Seeing P0357 on your car?
Every problem becomes a Case. Tell Redline what the car is doing: it shows what the evidence supports, what’s still missing, and what to check next, before you approve a repair.
“Inner pad ~1 mm. Outer pad 3 mm.”
Next: check the slide pins move freely before buying parts.