P0354
Ignition Coil D Circuit Malfunction
The engine computer has detected a problem in the ignition coil circuit for cylinder D. This can stop that cylinder from firing properly and cause misfires, rough running, or hard starting.
- SEV
- 4/5
- DRIVE
- CAUTION
- DIY
- $20–$180
- SHOP
- $120–$500
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Failed ignition coil
- Loose, corroded, or damaged coil connector or wiring
- Bad spark plug causing excessive coil load or misfire
Typical repair cost
DIY usually runs $20–$180. Typical shop repair lands around $120–$500, depending on the root cause.
01 / Definition
P0354 means the engine control module has detected an electrical fault in the primary or secondary ignition coil circuit for coil D. This is usually on a coil-on-plug system and may involve the coil itself, wiring, connector, power supply, ground, or the driver circuit in the ECM/PCM. The fault can cause one cylinder to lose spark, leading to a misfire and poor engine performance.
02 / Drive status
With caution. You may be able to drive short distances, but the engine may run poorly and can damage the catalytic converter if it misfires heavily. Do not keep driving if the check engine light is flashing or the engine is shaking badly.
03 / Symptoms
- Check engine light on
- Engine misfire
- Rough idle
- Poor acceleration
- Hard starting
- Reduced fuel economy
- Engine shaking under load
- Flashing check engine light in severe cases
04 / Causes
| 1 | Failed ignition coil | high |
|---|---|---|
| 2 | Loose, corroded, or damaged coil connector or wiring | high |
| 3 | Bad spark plug causing excessive coil load or misfire | medium |
| 4 | Failed ignition coil power supply, fuse, relay, or ground | medium |
| 5 | ECM/PCM driver circuit fault | low |
| 6 | Oil or water intrusion into the coil or connector | low |
05 / Diagnostic sequence
- 01Confirm the code and check for related misfire codes such as P0304 or other coil circuit codes.
- 02Inspect the ignition coil D connector and wiring for looseness, broken wires, corrosion, melted insulation, or oil intrusion.
- 03Check the coil fuse, power supply, and ground with a test light or multimeter.
- 04Swap the coil with another cylinder if the system allows it and see whether the misfire or fault follows the coil.
- 05Inspect the spark plug on that cylinder for wear, fouling, cracks, or excessive gap.
- 06Use a scan tool or oscilloscope to check coil command signals and circuit operation if the problem is not obvious.
- 07If wiring and the coil test good, check for ECM/PCM driver issues or a harness short.
06 / Repairs
| 1 | Repair loose, corroded, or damaged wiring and connector terminals | $20–$150 |
|---|---|---|
| 2 | Replace the ignition coil for cylinder D if it tests faulty | $40–$180 |
| 3 | Replace worn or fouled spark plugs as needed | $20–$120 |
| 4 | Repair power, ground, fuse, or relay issues in the ignition circuit | $30–$200 |
| 5 | Diagnose and repair ECM/PCM driver circuit problems if all external parts test good | $150–$800 |
07 / Related codes
08 / FAQ
What does ignition coil D mean?
It usually refers to the fourth ignition coil or the coil assigned to a specific cylinder, depending on the vehicle design. Check the service information for the exact cylinder mapping.
Can a bad spark plug cause P0354?
Yes. A worn or damaged spark plug can overload the coil or contribute to misfires, but the code usually points first to the coil circuit, wiring, or coil itself.
Will clearing the code fix the problem?
No. The code will come back if the electrical fault is still present.
Is this code serious?
Yes, it can be serious if the engine is misfiring. Continued driving can damage the catalytic converter and make the vehicle run poorly.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.