P0357 — Ignition Coil G Primary/Secondary Circuit Malfunction

What does P0357 specifically identify?

P0357 identifies a primary or secondary circuit malfunction involving ignition coil G. It points to that coil and its wiring, connector, power, ground, or related control circuit rather than a general ignition-system failure.

Can I continue driving with P0357 stored?

A short trip may be acceptable if the engine idles smoothly and runs without major hesitation, but an active misfire should be repaired promptly. Avoid further driving if the engine stalls, runs very rough, or loses significant power.

Does P0357 always mean ignition coil G is defective?

No. The coil may be electrically intact while its connector, wiring, power feed, ground, spark plug, plug lead, or control output is faulty. Testing the complete circuit prevents replacing a good coil unnecessarily.

How do I know the P0357 repair was successful?

Clear the stored code, operate the engine, and confirm that P0357 does not return while monitoring for new misfire codes. Smooth idle, normal acceleration, and the absence of repeat ignition faults support a successful repair.

P0357 indicates a fault with the primary or secondary circuit of ignition coil G — the component responsible for firing the spark plug in cylinder number seven. The engine control module continuously monitors the electrical signals going to and coming from each ignition coil. When those signals fall outside expected parameters, the module logs this specific trouble code. Unlike a simple open or short circuit, P0357 tells you the self-test of the coil assembly or its control circuitry failed, which means the problem could reside within the coil itself, the wiring feeding it, or even the driver circuitry inside the computer.

Your vehicle's ignition system works by having the PCM rapidly switch power to each coil on and off. Each coil then steps that voltage up dramatically and delivers it to its assigned spark plug at precisely the right moment. The module watches the coil's behavior during this process. If it detects no response, a weak response, or erratic behavior on consecutive ignition events under driving conditions, P0357 gets stored and the Check Engine Light illuminates. The code will not appear from a single glitch — the fault must repeat multiple times across a defined set of engine operating conditions before the module commits it to memory.

When technicians retrieve P0357, the associated freeze frame data is invaluable. This snapshot records engine load, RPM, temperature, and vehicle speed at the exact moment the fault occurred. Those values tell you what conditions to reproduce during testing, greatly narrowing down whether the problem appears only at idle, under heavy acceleration, or when the engine is cold. Many drivers first notice the issue during damp mornings or when the engine is under load, which gives you a starting point for your road test.

Common Symptoms

• Noticeable loss of engine power and hesitation during acceleration
• Difficulty starting the engine, especially in wet or humid conditions
• Rough idling or intermittent misfires whether the car is stationary or moving
• Check Engine Light remains illuminated on the dashboard
• Noticeable drop in fuel economy compared to normal driving patterns
• In severe cases, the CEL may flash rather than stay solid, indicating an active misfire

Likely Causes

• Internal failure of the ignition coil serving cylinder seven
• Corrosion, moisture intrusion, or oil contamination in the spark plug well
• Damaged wiring harness or loose connector at the coil mount
• Faulty driver circuit or outdated software within the PCM
• Worn, fouled, or incorrectly gapped spark plugs
• Partial short or open condition in the primary ignition control circuit
• Complete failure of the coil pack if your vehicle uses a multi-coil assembly

How to Diagnose

1. Connect an OBD2 scanner and verify that P0357 is the only code present — or note any additional codes, as related faults often point to the root cause. Record the freeze frame data before clearing anything.
2. Pull up manufacturer TSBs for your specific make, model, and year using your VIN. Many ignition-related faults have documented software calibrations or known fixes that resolve intermittent issues without parts replacement.
3. Perform a thorough visual inspection of the wiring and connector for coil G. Look for frayed wires, broken insulation, bent pins, green corrosion deposits, or any signs the connector is not fully seated.
4. If your scan tool supports bi-directional controls, run the actuator test for the ignition coil. A coil that fails to respond to a direct command from the scanner is confirmed as defective.
5. Swap the suspect coil with a known-good coil from another cylinder and clear the code. If P0357 moves to a different cylinder position, the coil itself is faulty. If it stays on cylinder seven, the problem lies in the wiring or PCM.
6. Remove and inspect the spark plugs in cylinder seven. Check for oil fouling, carbon buildup, eroded electrodes, or a gap that falls outside manufacturer specifications.

Repair Options and Costs

Ignition coil replacement — $150 to $380 for the part alone, with labor adding if you do not perform the swap yourself. A single failed coil is the most straightforward fix once diagnosed.

Spark plug replacement — $90 to $250 depending on plug type and local labor rates. Worn or fouled plugs in cylinder seven will cause the coil to work harder and fail prematurely.

Wiring or connector repair — $80 to $250 depending on whether you need a simple terminal cleanup, a new connector pigtail, or full harness repair. Sealing a moisture-damaged well or patching a chafed wire often resolves intermittent faults at the lower end of this range.

Total Cost to Fix P0357

Expect to pay between $80 and $380 total for parts and labor at an independent shop. The least expensive scenario — cleaning corrosion from a connector and replacing worn plugs — sits at the bottom of that range. A full coil replacement with labor pushes toward the higher end. Diagnosing before buying parts is the smartest move here, because the coil itself is rarely the culprit when wiring or plug condition are still unknown.

Can You Drive with P0357?

Use caution. A faulty ignition coil causes sustained misfires that dump unburned fuel into the exhaust stream. That raw fuel overwhelms the catalytic converter and can cause it to overheat and fail — an extremely expensive repair. If the Check Engine Light is flashing, stop driving immediately and have the vehicle towed. A steady CEL with mild symptoms allows limited driving to a repair facility, but heavy loads, hard acceleration, and extended trips should be avoided until the issue is resolved.

Related OBD2 Codes

• P0300: Random/Multiple Cylinder Misfire Detected
• P0301: Cylinder 1 Misfire Detected
• P0302: Cylinder 2 Misfire Detected
• P0303: Cylinder 3 Misfire Detected
• P0304: Cylinder 4 Misfire Detected
• P0305: Cylinder 5 Misfire Detected