Ignition Coil D Primary/Secondary Circuit Malfunction
The P0354 code indicates a malfunction in the primary or secondary circuit of ignition coil D (typically cylinder 4). This circuit includes the coil itself, its power supply, ground, and the control signal from the engine control module (ECM). A fault can cause weak or no spark, leading to misfires, reduced power, and increased emissions.
01. Most Common Causes
- Faulty ignition coil D
- Open or shorted wiring in coil circuit
- Poor electrical connection at coil connector
- Failed ECM (rare)
02. Symptoms You Will Notice
- Engine misfire (especially cylinder 4)
- Check Engine Light on
- Rough idle, hesitation, or loss of power
- Increased fuel consumption
03. Step-by-Step Diagnosis
Step 1: Scan for codes and verify P0354 is present.
Step 2: Visually inspect ignition coil D and its wiring for damage or corrosion.
Step 3: Swap coil D with another cylinder; if code moves, replace the coil.
Step 4: Test power and ground at coil connector with a multimeter.
Step 5: Check ECM output signal using a lab scope or test light.
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 reduce fuel economy.
How much does it cost to fix?▼
Typically $100-$200 for parts and labor, depending on coil price and accessibility.