Ignition Coil I Primary/Secondary Circuit Malfunction
The P0359 code indicates a malfunction in the primary or secondary circuit of ignition coil I (cylinder 9). This circuit includes the coil itself, wiring, connectors, and the engine control module (ECM) driver. The ECM monitors the coil's primary circuit for proper voltage and current; if it detects an open, short, or excessive resistance, it sets this code. A faulty coil can cause misfires, reduced engine performance, and increased emissions.
01. Most Common Causes
- Faulty ignition coil I
- Open or short in coil wiring or connector
- Damaged ECM or poor ECM ground
- Corroded or loose electrical connections
02. Symptoms You Will Notice
- Engine misfire (especially under load)
- Rough idle or hesitation
- Check Engine Light illuminated
- Decreased fuel economy and power
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect ignition coil I wiring and connector for damage or corrosion.
Step 3: Swap coil I with another cylinder and see if the code moves.
Step 4: Test coil primary and secondary resistance with a multimeter (specs vary by vehicle).
Step 5: Check for power and ground at coil connector with key on.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended. Driving with a misfire can damage the catalytic converter and other engine components. Have it diagnosed promptly.
How much does it cost to fix?▼
Replacing a single ignition coil typically costs $150-$300 including parts and labor. Diagnosis may add $50-$100.