The dreaded check engine light illuminating your dashboard can be a source of anxiety for any driver. One common culprit behind this warning is the EOBD/OBDII error code P0355, which indicates a problem with the ignition coil “E” primary/secondary circuit. This article will delve into the intricacies of this error code, explaining its meaning, potential causes, symptoms, and diagnostic steps.
What Does the P0355 Code Mean?
Modern vehicles predominantly utilize a Coil-on-Plug (COP) ignition system, where each cylinder has a dedicated ignition coil controlled by the Powertrain Control Module (PCM). The P0355 code specifically points to a malfunction in the electrical circuit of ignition coil “E.” This malfunction can manifest as an open circuit (break in the wiring), a short circuit (unintended connection), or a problem within the coil itself. The PCM constantly monitors these circuits, and when it detects an anomaly in the signal from coil “E,” it triggers the P0355 code and illuminates the check engine light. In some vehicles, the PCM might also deactivate the corresponding fuel injector to prevent further damage.
Recognizing the Symptoms of a P0355 Code
While the illuminated check engine light is the most obvious symptom, a P0355 code can also manifest through various performance issues:
- Engine Misfire: This is a common symptom, often noticeable as a rough idle, lack of power, or hesitation during acceleration. The misfire occurs because the affected cylinder isn’t igniting the fuel-air mixture properly. The misfire might be constant or intermittent.
- Reduced Fuel Efficiency: A misfiring cylinder can lead to decreased fuel economy as the engine works harder to compensate for the lost power.
- Rough Idle: The engine might vibrate excessively or run unevenly at idle due to the misfiring cylinder.
- Hard Starting: In some cases, the engine might be more difficult to start.
Common Causes of the P0355 Error Code
Several factors can contribute to a P0355 error code:
- Wiring Issues: Damaged, corroded, or loose wiring in the ignition coil circuit is a frequent cause. This includes the wiring harness connecting the coil to the PCM and the connectors at both ends. Rodents chewing on wires is a surprisingly common culprit.
- Faulty Ignition Coil: The ignition coil itself might be defective due to internal damage or wear and tear.
- PCM Problems: Although less common, a malfunctioning PCM can also trigger this code. This could be due to internal faults or damaged wiring connected to the PCM.
- Short to Voltage or Ground: A short circuit in the wiring can disrupt the electrical signal and trigger the P0355 code.
- Bad Connector: A damaged or corroded connector at the ignition coil or PCM can create a poor connection.
Diagnosing and Fixing the P0355 Code
Troubleshooting the P0355 code involves a systematic approach:
- Visual Inspection: Begin by visually inspecting the wiring and connectors associated with ignition coil “E.” Look for any signs of damage, corrosion, or loose connections. Wiggle the wiring and connectors while the engine is running to see if it induces a misfire.
- Testing the Coil Driver Circuit: With the engine off and the coil disconnected, use a multimeter to check for voltage and continuity in the coil driver circuit. This will help determine if there’s an open circuit, a short circuit, or a problem with the PCM driver signal.
- Testing the Ignition Coil: If the driver circuit is functioning correctly, test the ignition coil itself using a multimeter or a dedicated coil tester. This will confirm whether the coil is capable of producing the necessary spark.
- Checking for PCM Issues: If all other components check out, a faulty PCM might be the culprit. However, PCM failure is relatively rare and should only be considered after thoroughly testing all other possibilities. Remember, a wiring problem can damage the PCM. Always fix any wiring issues before replacing the PCM.
Conclusion
The EOBD/OBDII error code P0355 indicates a problem with the ignition coil “E” circuit, potentially leading to engine misfires and performance issues. By understanding the underlying causes and following a systematic diagnostic approach, you can effectively identify and resolve the issue, restoring your vehicle’s smooth operation and fuel efficiency. If you are not comfortable working on your car’s electrical system, it is recommended to consult a qualified mechanic for diagnosis and repair.
