Ignition coils create the high voltage the spark plugs need to ignite the air-fuel mixture inside the combustion chamber. They are crucial in preventing stumbles and misfires. Whenever your powertrain control module (PCM) detects a problem with ignition coil E, it triggers the trouble code P0355. This article mainly explains the P0355 code meaning, symptoms, and causes.
P0355 Code Definition
P0355 code stands for “Ignition Coil ‘E’ Circuit Malfunction.”
What Does the P0355 Code Mean?
The P0355 code indicates that your powertrain control module (PCM) detects a potential problem either in the primary or secondary circuit for ignition coil “E.” The ignition coil E is coil number 5 installed on engine cylinder number 5.
The ignition system takes low voltage from the battery and converts it into high voltage to ignite the air-fuel mixture in the combustion chamber. The low-voltage side of the system is called the primary circuit.
The primary circuit contains a switching unit (e.g., ignition module or PCM), ignition switch, a trigger mechanism (e.g., crankshaft sensor), primary coil windings, and vehicle battery. The high-voltage side of the system is known as the secondary circuit. In the case of the latest car, the secondary circuit contains spark plugs and coil packs.
A coil pack converts the low voltage of the primary circuit to the high voltage of the secondary circuit, which is used by the spark plug to generate the spark.
There are hundreds of wires on the primary side and thousands of wires on the secondary. A current flow through the primary side of the coil generates a magnetic field around the windings. The current is then disturbed by a switching device such as a PCM. As a result, the magnetic field collapses and induces a voltage in the windings.
At the same time, the collapsed magnetic field produces a voltage in the secondary windings. The output voltage increases to thousands of volts due to the increased number of turns of wire in the secondary winding. The generated voltage is adequate to fire the spark plug. The generated spark by the spark plug is used to ignite the air-fuel mixture in the combustion chamber.
Whenever your PCM observes that your ignition coil ‘E’ is not working properly, it triggers the P0355 trouble code on your car dashboard.
Symptoms of P0355 Code
- Poor engine performance
- Rough or erratic idle
- Illuminated check engine light
- Hard to start the vehicle
- Poor fuel economy
- Engine misfiring
- Poor acceleration
Causes of P0355 Code
- Blockage in air passages of the throttle body due to carbon build-up
- Damaged or bad ignition coils
- Defective ignition coil connectors
- Bad EGR system
- Short or open in the ignition coil wiring harness
- Intake manifold vacuum leaks
- Damaged spark plug connectors and wiring
- Poor electrical connections at the coil
- Short or open COP driver circuit
- Bad spark plug
- Bad PCM
How to diagnose the P0355 Code?
Follow the following steps to diagnose the P0355 engine code:
- Take an OBD-II scanner to scan the P0355 code saved in the PCM memory.
- Use the freeze frame data to check the stored trouble codes.
- After inspection and major repairs, clear the codes. Test drive your vehicle. If the P0355 code returns, then move for further inspection.
- Inspect the coil pack of the vehicle.
- Inspect the spark plug for corrosion or damage.
- Properly inspect the connectors for damage.
- Perform a visual inspection of the ignition coil ‘E’ connections and wiring.
- Properly inspect the primary ignition coil for damage.
- Inspect the intake manifold to check the vacuum leaks.
- Test the PCM if no fault has been found up until this point.
Common P0355 Code Diagnostic Mistakes
- Not measuring the hertz signal that the PCM should send to the coil pack
- Replacing the parts without testing
- Not inspecting the connections and wires before replacing the spark plug or ignition coil
- Replacing the unnecessary parts
- Clearing the PCM memory without first confirming the problem
What repairs can fix the P0355 Code?
One or more of the following repairs can fix the P0355:
- Fixing or replacing the damaged coil pack wires
- Replacing the coil pack for cylinder number 5
- Repairing or replacing the bad wiring harnesses
- Replacing the bad spark plug located at cylinder number 5
- Throttle body cleaning
- Fixing the intake manifold leaks
- Replacing or reprograming the PCM if needed
How serious is the P0355 code?
The P0355 code is considered a serious trouble code. It makes the vehicle hard to drive. Driving with a misfiring engine has a negative effect on your engine. Because if one of your engine cylinders is stalled, the other cylinders will have to work harder to keep the car running. This puts extra pressure on other cylinders and can cause components such as the crankshaft, piston, spark plug, piston rings, and other coil packs to wear out faster.
Repair Cost of P0355 Code
The repairing cost of the P0355 code varies according to the labor cost, vehicle model, and the repair of the relevant part. To fix the P0355, you may need one of the below-given repairs:
| Parts | Cost |
| Ignition coil replacement | $160 to $220 |
| Vacuum leak repair | $70 to $380 |
| Spark Plug replacement | $60 to $260 |
| PCM replacement | $240 to $3,000 |
FAQ Section
How do I fix error code P0355?
- Fix or replace the damaged coil pack wires
- Replace or reprogram the PCM if needed
- Replace the bad coil pack
- Repair or replace the bad wiring harnesses
- Fix the intake manifold leaks
- Replace the bad spark plug located at cylinder number 5
- Throttle body cleaning
Is it OK to drive with a bad ignition coil?
Yes, it is possible to drive with a bad ignition coil, but it is not advisable. Driving with a bad waste spark ignition system won’t be possible. Driving with a faulty coil pack can damage other components of the engine.
Can a bad spark plug cause P0355?
Yes, a bad spark plug can trigger the P0355 engine code.