The ignition coil takes voltage from the battery, converts it into a high-voltage current, and transfers it to the spark plugs. The spark plugs use this high-voltage current to generate a spark. An issue with the ignition coil of cylinder number 4 may cause your vehicle powertrain control module (PCM) to trigger the P0354 code. This article explains the P0354 code meaning, symptoms, and causes.
P0354 Code Definition
P0354 code stands for “Ignition Coil ‘D’ Circuit Malfunction.”
What Does the P0354 Code Mean?
The P0354 code indicates that your powertrain control module (PCM) monitors a potential problem either in the primary or secondary circuit for ignition coil “D”. The ignition coil D is coil number 4 installed on engine cylinder number 4.
The ignition coil is responsible for properly igniting the air-fuel mixture in the engine’s combustion chambers.
The coil is basically a transformer that takes low-voltage current from the vehicle battery and converts it into high voltage according to the spark plug requirements. The spark plug uses this high-voltage current to generate a spark which is used to ignite the fuel-air mixture and make the combustion process successful.
The ignition coil of your vehicle contains a “primary” winding and a “secondary” winding. A switching device is used to trigger the primary winding so that the secondary winding generates the needed high-voltage spark.
When something goes bad with the cylinder #4 ignition coil, the PCM of your car triggers the P0354 engine code.
Causes of P0354 Code
- Faulty ignition coils
- A leaking intake manifold vacuum
- Poor electrical connections at the coil
- Damaged spark plug wires
- Bad spark plugs
- Open or short in the ignition coil wiring harness
- Corroded, damaged, or defective ignition coil connectors
- Blockage in air passages of the throttle body due to carbon build-up
- Short or open COP driver circuit
- Bad IAC valve
- Faulty EGR/intake
- Bad PCM
Symptoms of P0354 Code
- Rough or erratic idle
- Poor engine performance
- Illuminated check engine light
- Hard to start the vehicle
- Poor fuel economy
- Engine misfiring
- Poor acceleration
How to diagnose the P0354 Code?
Follow the following steps to diagnose the P0354 trouble code:
- Verify the existence of the P0354 by using an OBD-II scan tool.
- Use the freeze frame data to find the main issue. Continue the troubleshooting based on the other trouble codes you may find.
- Clear the codes. Take your car for a test drive. If the P0354 code returns, perform a deep inspection.
- Visually inspect the wiring and connections of the coil system.
- Properly inspect the connectors for damage.
- Inspect the coil pack of the vehicle.
- Inspect the spark plugs for damage.
- Check the vacuum leaks by using a vacuum gauge. A vacuum leak is one of the major reasons for an engine misfire.
- Test the ignition coil installed at cylinder number 4 by using a scan tool like a multimeter. If the coil is faulty, replace it.
- Perform a compression test to test the compression system of the engine.
- Test the PCM if no fault has been found up until this point.
Common P0354 Code Diagnostic Mistakes
- Diagnosing a bad ignition coil when the actual cause of the issue was a leak in the vacuum.
- Replacing the spark plugs without fixing the vacuum leak.
- Replacing the unneeded parts.
- Not clearing the PCM memory after fixing the issue
What repairs can fix the P0354 Code?
- Repairing or replacing the intake manifold vacuum leak
- Replacing or repairing the ignition coils
- Replacing the damaged ignition coil connectors
- Replacing or repairing the damaged wiring to the ignition coils.
- Replacing the bad spark plugs
- Replacing or reprograming the PCM if needed
Repair Cost of P0354 Code
To fix or repair the P0354 code, you need one or more of the following repairs:
| Parts | Cost |
| Ignition coil replacement | $160 to $220 |
| PCM replacement | $240 to $3,000 |
| Fuel Injector replacement | $340 to $860 |
| Spark Plug replacement | $60 to $260 |
| Vacuum leak repair | $70 to $380 |
How serious is the P0354 Code?
The P0354 is considered a serious diagnostic trouble code. The car may fail to start if it has a P0354 code. It may lead to different serious problems, such as poor engine performance, higher fuel consumption, or engine stalling. Driving with this code is very risky. Therefore, you should fix this code as soon as possible.
FAQ Section
Which coil is P0354?
The P0354 trouble code represents an issue with ignition coil “D”, which is the coil on cylinder number 4.
How do you fix a cylinder 4 misfire?
The following repairs can fix the cylinder 4 misfire:
- Replacing the bad spark plug
- Repairing or replacing the intake manifold vacuum leak
- Replacing or repairing the damaged wiring to the ignition coils
- Replacing or repairing the ignition coils
- Replacing the damaged ignition coil connectors
- Replacing or reprograming the PCM
What is the primary purpose of an ignition test?
The test aims to estimate whether the fabric/materials can prevent the flame from spreading. The ignition test focuses on if the flame is extinguished eventually, disregarding how wide the area burned before flaming off.
Can a bad spark plug cause P0354?
Yes, a faulty spark plug can cause P0354. If the spark plug located at cylinder #4 is not producing sparks properly, it may affect the performance of the coil “D” and lead to the P0354 engine code.