P0355 — Ignition Coil “E” Primary/Secondary Circuit #

Note: The code description may vary depending on the vehicle manufacturer (OEM).

• P0355: Ignition Coil “E” Primary/Secondary Circuit Malfunction (General/OEMs)
• P0355: Ignition Coil 5 Circuit Malfunction (Ford, Toyota, GM)
• P0355: Cylinder 5 Ignition Coil Circuit Error (Hyundai, Kia)

Summary of DTC P0355 #

The P0355 diagnostic trouble code (DTC) points to a problem within the electrical circuit for ignition coil “E”—commonly corresponding to coil number 5 on most engines. When this code is triggered, your vehicle’s engine control module (ECM) has detected an interruption or irregularity in the primary (input) or secondary (output) circuit associated with this coil. Ignition coils are crucial for transforming battery voltage into the high voltage needed to fire the spark plugs. A fault here can cause misfires, rough running, and decreased engine performance. While this issue is not always catastrophic, ignoring it can lead to engine damage or increased emissions.

Frequent Symptoms for DTC P0355 #

When DTC P0355 appears, your vehicle typically displays a set of clear warning signs. These symptoms arise because the ignition coil is directly responsible for firing the spark plug in one cylinder, so any loss of function can disrupt normal engine operation.

• Illuminated Check Engine Light (CEL)
• Engine misfire, especially at idle or acceleration
• Poor fuel economy
• Rough idle or stalling
• Hesitation or lack of power
• Possible difficulty starting the engine

Probable Causes of DTC P0355 (Ranked by Frequency) #

There are several potential reasons why the P0355 code may appear. Understanding the most common causes can help prioritize diagnostic efforts and repairs. Most often, this code indicates an issue with coil “E” itself, but wiring and connector issues are also prevalent.

1. Faulty ignition coil “E” (coil #5): Internal failure or short/open circuit
2. Damaged or corroded wiring: Issues in the harness connected to the ignition coil
3. Loose, unplugged, or corroded ignition coil connector
4. Faulty engine control module (ECM) (rare)
5. Blown fuse in the ignition circuit

Step-by-Step Diagnostic for Code P0355 #

A thorough stepwise approach is essential for accurately diagnosing P0355. This ensures you address the root cause and avoid unnecessary part replacements. Here’s how a professional technician would tackle the process:

• Verify and record the code with an OBD-II/EOBD scan tool. Clear the code and see if it returns.
• Inspect the ignition coil “E” and corresponding wiring harness for visible signs of damage, corrosion, or loose connections.
• Check the ignition coil connector for bent pins, corrosion, or poor fit.
• Test coil “E” resistance with a multimeter to compare against OEM specifications (refer to your vehicle service manual).
• Swap coil “E” with another cylinder’s coil (if applicable) and see if the fault code follows the coil or stays at cylinder 5.
• Check for proper voltage and ground at the coil connector with ignition on.
• Inspect fuses and relays related to the ignition system.
• If all else checks out, consider ECM testing or reprogramming as a last resort.

Possible Repairs for Code P0355 #

Once you’ve identified the culprit for P0355, targeted repairs can restore your engine’s performance and reliability. Here are the most effective fixes linked to the common causes:

• Replace the faulty ignition coil “E” (coil #5)
• Repair or replace damaged wiring harness sections
• Clean or replace corroded connectors and terminal pins
• Replace blown fuse or faulty ignition relay as needed
• Reprogram or replace the ECM (only if confirmed faulty—rare)

Is It Safe to Drive with Code P0355? #

Driving with code P0355 is NOT recommended for extended periods. While you may be able to drive short distances, a misfiring cylinder can lead to catalytic converter damage, increased emissions, and potential engine wear. The loss of one ignition coil could also cause unpredictable engine behavior, which may compromise safety in traffic or harsh conditions. Address this issue promptly to avoid more costly repairs down the road.

Vehicles Most Commonly Affected by DTC P0355 #

While P0355 can appear on any OBD-II compliant vehicle, certain makes and models are more frequently reported with this code due to their coil-on-plug ignition systems or known wiring vulnerabilities.

• Ford F-150, Explorer, Mustang
• Toyota Camry, Corolla, Tacoma
• Hyundai Sonata, Elantra
• Kia Optima, Sorento
• Chevrolet Silverado, Malibu
• Chrysler 300, Dodge Charger

Common Mistakes & Best Practices for DTC P0355 #

Misdiagnosis and unnecessary repairs are common with ignition circuit codes. Here are the pitfalls to avoid and the best practices to ensure a swift, accurate fix:

• Replacing the ignition coil without first checking wiring and connectors
• Overlooking blown fuses or relays that supply power to the coil
• Not swapping coils to confirm the fault location before replacing parts
• Failing to clear codes and road test after repairs to confirm resolution
• Always consult the vehicle-specific wiring diagram and resistance specs from the OEM

Express FAQ — Code P0355 #

Got a quick question about P0355? Here are some fast answers:

• Q: Can a bad spark plug cause P0355?
  A: Unlikely. The code specifically relates to the coil’s electrical circuit, not the plug itself. However, always inspect the spark plug for fouling or damage when diagnosing ignition issues.
• Q: Will replacing only the faulty coil solve the problem?
  A: In most cases, yes, if the coil is the root cause. But always check wiring and connectors, as these are frequent culprits. If your vehicle has high mileage, consider replacing all coils to prevent future failures.