Ignition Coil G Primary/Secondary Circuit Malfunction
The P0357 code indicates a malfunction in the primary or secondary circuit of ignition coil G (typically coil number 7 on V8 engines or coil 6 on some configurations). This circuit includes the coil itself, wiring, connectors, and the engine control module (ECM) driver. The ECM detects an electrical fault such as an open, short, or excessive resistance, preventing proper spark generation. This can lead to misfires, reduced power, and increased emissions.
01. Most Common Causes
- Faulty ignition coil G
- Open or shorted wiring in coil circuit
- Poor electrical connection at coil or ECM
- Failed ECM (rare)
02. Symptoms You Will Notice
- Engine misfire and rough idle
- Check Engine Light illuminated
- Reduced engine power and acceleration hesitation
- Increased fuel consumption
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect ignition coil G and its wiring for damage, corrosion, or loose connections.
Step 3: Swap coil G with a known good coil from another cylinder and clear codes. If the code moves to the new cylinder, replace coil G.
Step 4: If code remains, test coil power and ground circuits with a multimeter (should see battery voltage and good ground).
Step 5: Check ECM driver by using a test light or oscilloscope on the coil control wire while cranking; if no signal, suspect ECM issue.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the misfire can damage the catalytic converter and cause poor performance. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
Replacing a single ignition coil typically costs $50-$150 including parts and labor. If wiring repairs are needed, costs may be higher.