Ignition Coil Secondary Circuit Malfunction (P2305)
The P2305 code indicates a problem in the secondary circuit of ignition coil number 5 (or the specific coil identified by the manufacturer). The secondary circuit includes the coil output, spark plug wire, and spark plug. The Powertrain Control Module (PCM) detects an abnormal voltage or current in this circuit, often due to excessive resistance or a short. This can lead to misfires, reduced engine performance, and increased emissions.
01. Most Common Causes
- Faulty ignition coil
- Worn or damaged spark plug
- Faulty spark plug wire or boot
- Carbon tracking on coil or spark plug
- Open or short in wiring to coil
02. Symptoms You Will Notice
- Engine misfire or rough idle
- Check Engine Light illuminated
- Reduced fuel economy
- Loss of power during acceleration
- Engine may hesitate or stumble
03. Step-by-Step Diagnosis
Step 1: Scan for codes and note freeze frame data to identify the affected cylinder.
Step 2: Visually inspect the ignition coil, spark plug wire, and spark plug for damage, carbon tracking, or corrosion.
Step 3: Swap the suspect coil with another cylinder and see if the code moves; if so, replace the coil.
Step 4: Test the spark plug wire resistance (should be low, typically under 10k ohms) and replace if out of spec.
Step 5: Check the spark plug condition and gap; replace if worn or fouled.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances with P2305 as it can cause catalytic converter damage due to unburned fuel. Short trips to a repair shop are acceptable.
How much does it cost to fix?▼
The cost typically ranges from $150 to $300, including parts (ignition coil, spark plugs, wires) and labor. DIY replacement can be cheaper.