What are the P0354 Code Symptoms and Causes? | How to Fix P0354?

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 in the ignition coil “D” circuit’s operation 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 P0354 Code Mean?

The P0354 code indicates that your powertrain control module (PCM) detects 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.

P0354 code

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.

If a vehicle has a P0354 code stored, it will not be able to ignite that mixture with the correct timing, and the engine will run roughly or stall.

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?

  • Use an OBD2 scanner to check the trouble codes saved in the PCM memory.
  • Use the freeze frame data to check what’s going on. Continue the troubleshooting based on the other trouble codes you may find.
  • Clear the codes.
  • Test drive your vehicle. If the P0354 code return, then move for further 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 plug for damage.
  • Use a vacuum gauge to check the vacuum leaks. A vacuum leak is one of the major reasons for an engine misfire.
  • Properly inspect the primary ignition coil. If the coil is damaged, 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:

PartsCost
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

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 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.

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 are the causes of the P0354 code?

  • Faulty ignition coils
  • Faulty EGR/intake
  • A leaking intake manifold vacuum
  • Poor electrical connections at the coil
  • The short or open COP driver circuit
  • Damaged spark plug wires
  • Bad spark plugs
  • Open or short in the ignition coil wiring harness
  • Bad IAC valve
  • Corroded, damaged, or defective ignition coil connectors
  • Blockage in air passages of the throttle body due to carbon build-up
  • Bad 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.

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