P0357
UniversalIgnition Coil G Primary/Secondary Circuit Malfunction
Medium SeverityThis code indicates that the Powertrain Control Module (PCM) has detected an issue with the primary or secondary circuit of the Ignition Coil G. A malfunction in this circuit can prevent the ignition coil from generating the necessary high voltage to ignite the spark plug, leading to engine misfires.
⚠️ Before You Begin (Safety First)
Always allow the engine to cool completely before working on ignition system components. Disconnect the battery before performing any electrical repairs to prevent electrical shock or damage to the vehicle's electrical system. Be aware that ignition systems involve high voltage; exercise extreme caution.
Common Symptoms
- Check Engine Light illuminated
- Engine misfire
- Rough idle
- Reduced engine power
- Poor fuel economy
- Engine hesitation or stumbling during acceleration
Common Causes
- Faulty ignition coil (Coil G)
- Damaged or corroded wiring/connector to Ignition Coil G
- Short circuit or open circuit in the ignition coil circuit
- Faulty spark plug associated with Ignition Coil G
- Problem with the Powertrain Control Module (PCM)
Frequently reported on: General/Universal, Ford F-150 (2004-2010), Chevrolet Silverado (2000-2007), Honda Accord (2003-2007)
Diagnostic Steps
- Inspect the wiring and connector to Ignition Coil G for damage, corrosion, or loose connections. Repair as needed.
- Remove Ignition Coil G and inspect for any visible damage or signs of overheating.
- Test the resistance of Ignition Coil G using a multimeter, comparing it to manufacturer specifications. Replace if out of spec.
- Swap Ignition Coil G with a known good coil from another cylinder (if applicable) and see if the code changes to the new cylinder's coil code. If it does, replace the coil.
- Inspect and replace the spark plug associated with Ignition Coil G.
- Clear the code and test drive the vehicle to confirm the repair.
👨🔧 When to Call a Professional
If you've replaced the Ignition Coil G and the spark plug, and inspected the wiring but the P0357 code persists, it's highly recommended to consult a professional. The issue could be with the PCM or a more complex wiring harness fault that requires specialized diagnostic tools.
Commonly Asked Questions
What does Ignition Coil G refer to?
The letter 'G' indicates a specific cylinder's ignition coil. The exact cylinder it corresponds to varies by vehicle manufacturer and engine configuration. You'll need to consult your vehicle's service manual to identify Coil G.
Can I drive with a P0357 code?
While it might be possible to drive, it's not recommended for extended periods. A persistent misfire can lead to reduced power, poor fuel economy, and potentially damage the catalytic converter over time. It's best to address the issue promptly.
Do I need to replace all ignition coils if one fails?
Not necessarily. If only one coil (Coil G) is showing a fault, you can often just replace that specific coil. However, if coils are original and high mileage, replacing them in a set (e.g., all on one bank or all eight) can be a proactive maintenance step.
How can I tell if the coil or the wiring is the problem?
After visually inspecting the wiring for obvious damage, you can use a multimeter to test for proper voltage and ground signals at the coil connector. If these are correct, the coil itself is likely faulty. If not, the wiring or PCM is the issue.
What's the difference between primary and secondary circuit malfunction?
The primary circuit is the low-voltage side that charges the coil, controlled by the PCM. The secondary circuit is the high-voltage side that delivers spark to the plug. A malfunction in either means the coil isn't working correctly to produce spark.