How to Fix P0355 OBD2 Code

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P0355 is a Diagnostic Trouble Code (DTC) which means that there is a potential problem at the “Ignition Coil ‘E’ circuit’ at the primary or secondary level. This code is observed if the powertrain control module detects a problem at the computer side (primary) or the spark plug side (Secondary).

Meaning of P0355

The primary purpose of ignition coils is the ignition of fuel/air mix in the combustion chambers of the engine. If there is an electrical problem with any of these ignition coils (coil B if the DTC code p0355 is observed), the engine cannot run smoothly. It may result in misfiring by the engine. 

Constant or intermittent engine fire and/ or illumination of malfunctioning indicator lamps may be the symptoms of this particular problem. P0355 OBD2 code is generic and can be observed in most vehicles at some point in time. Even though this problem may not shut down your car completely on most occasions, there is still a need to attend to this problem immediately. 

As, if left unattended, it can cause serious damage to your car’s engine. However, the good news is that diagnosing and repairing this issue is not very difficult or costly. 

In this article, we shall discuss the diagnosis, repairing, and other important information related to the OBD2 P0355 code in detail. So, let’s get started with understanding this error code in further detail.

Causes of P0355 Code

This code may be generated due to several causes or problems. The most commonly occurring causes are listed below:

  1. An issue with the powertrain control module. Outdated software is among the most common issues with PCM.
  2. Cylinder 5 ignition coil may be defective.
  3. Ignition coil B may be defective.
  4. Short-circuiting in the ignition coil.
  5. Open circuiting in the ignition coil.
  6. Spark plugs may be defective.
  7. Fault with an electronic body or air control valve.
  8. The Air passageway of the engine may be clogged up due to carbon buildup.
  9. Broken connector locks.
  10. Bad coil.

How to Diagnose P0355 code?

With enough basic knowledge and know-how, you may carry out diagnoses for your vehicle. Alternatively, you may go to a certified technician or a mechanic to get the real issue diagnosed. In either case, the first step would be to use an OBD-2 scanner to look for the error code. Then, the code may be erased and a test drive is conducted to ensure that the error exists.

How to Diagnose P0355 code?

At the next stage, the actual physical inspection needs to be done to find the root cause of the problem. This is done by inspecting the circuits and wiring of the ignition coil B. Close attention should be paid to the crank signal, as a problematic crank signal can also result in a p0355 error code.

If everything seems fine till this stage, switch the coil and its relevant spark plug, and use a good cylinder to spark. Clear and code and take a test drive. If the same code is recorded again, it means that the problem is with the coil or the spark plug. Both need to be tested one by one to ascertain the actual cause of the problem. Once it is done, the repairing/ fixing problem can be initiated. 

Tools Required for Diagnosis:

If you set out to perform the diagnosis yourself, it is recommended to source the following tools for reliable diagnosis:

  1. An OBD-2 scanner.
  2. Auto repair manual.
  3. Multimeter.
  4. Basic hand tools.

Common Mistakes to Avoid During the P0355 Code Diagnosis:

The fundamental principle of diagnosis is to always conduct a thorough diagnosis. At times, the problem is not with the spark plug or the ignition coil. Instead, the error code could be due to a leaking vacuum. Replacing or trying to repair coil or spark plugs without thoroughly inspecting the whole system could lead to ineffective repair.

How to Fix this Code?

On most occasions, certain repairs or replacements need to be performed to fix this code. The most common fixes for P0355 are as follows:

  1. Replacing the faulty spark plugs (there could be more than one faulty plug at a time).
  2. Ignition coil B replacement.
  3. Idle air control valve replacement.
  4. Replacing the electronic body.
  5. Replacing or repairing the ignition coil wiring harness and/ or circuit connectors.
  6. Built-up carbon in the throttle body or engine’s air passageway may be cleaned.

Tips to Avoid P0355 Code:

Once you have corrected the P0355 error code and repaired all the essential parts, you need to be careful in the future to avoid the recurrence of this error code. 

The following tips may prove to be helpful in this regard.

  1. Keep additional spark plugs in your car for timely replacement, as faulty spark plugs are often the cause of this error.
  2. Make sure to periodically clean the carbon buildup in the engine’s air passageway.
  3. Make sure that the wiring harness and connectors to the ignition coil are inappropriate shapes at all times.

What is the Estimated Cost of Repair?

If you go to a professional mechanic for diagnosis, a professional may take around 1 hour to diagnose. While the costs may vary, typically he or she will charge anywhere from $50 to $150 per hour for the diagnosis. Then, you need to pay for the repair or part replacement to solve the issue. Again, it will depend upon the particular cause of the problem that is generating the p0355 code. However, you may expect to pay an additional $50 to $200, depending upon the extent of repair/ replacement work and the replaced parts.

Overall, remember that the sooner you get to diagnose and repair your vehicle, the less costly it may be. As, with every passing day, the underlying issue may be causing damage to other parts as well. Prolonged p0355 problems can also impact the working of your vehicle’s engine in the long run.