Ignition Coil E Primary/Secondary Circuit Malfunction
The P0355 code indicates a malfunction in the primary or secondary circuit of ignition coil E. This coil is responsible for providing the spark to cylinder 5 (or the specific cylinder designated as 'E' by the manufacturer). The Powertrain Control Module (PCM) monitors the voltage and current in the coil's primary circuit and the firing voltage in the secondary circuit. When the PCM detects an abnormal condition—such as an open or short circuit, excessive resistance, or a lack of spark—it sets this code. Common causes include a faulty ignition coil, damaged wiring or connectors, a bad spark plug, or a PCM issue.
1. Most Common Causes
- Faulty ignition coil on cylinder 5 (coil E) — internal short or open circuit
- Damaged wiring or connectors in the primary control circuit or secondary high-voltage circuit — short to ground, short to power, or open circuit
- Loose or corroded connection at the ignition coil connector
- Failed ignition driver inside the PCM/ECM
- Defective spark plug on cylinder 5 or incorrect spark plug gap causing high secondary resistance
2. Symptoms You Will Notice
- Engine misfire (especially under load)
- Check Engine Light illuminated
- Rough idle or hesitation
- Decreased fuel economy
- Possible engine stalling
3. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0355 is present. Check for additional misfire codes.
Step 2: Visually inspect ignition coil E, its wiring, and connector for damage, corrosion, or loose connections.
Step 3: Swap coil E with another cylinder's coil. If the misfire moves, replace the coil.
Step 4: Test the coil's primary and secondary resistance with a multimeter and compare to specifications.
Step 5: Inspect the spark plug and wire for cylinder E; replace if worn or damaged.
4. 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 cause poor performance. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for a single ignition coil replacement, plus labor if done by a shop. DIY cost is lower.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.