Fix P0355: Mechanic’s solutions that WORKED

The code P0355: Ignition Coil “E” Primary/Secondary Circuit Malfunction points out a fault in the ignition coil’s primary or secondary circuit, and it’s most likely caused by issues with the coil itself, wiring, or the connector.

P0355 quick overview

Meaning	P0355: Ignition Coil “E” Primary/Secondary Circuit Malfunction
Is it serious?	Yes, it can affect the vehicle’s performance, fuel efficiency, and emissions.
Possible causes	– Damaged or faulty ignition coil – Corroded terminals on the coil connector – Wiring issues related to the ignition coil – Faulty or damaged connectors – Issues with the Powertrain Control Module (PCM)
How to diagnose?	Scan for Codes: Always start by scanning the vehicle to confirm the presence of the P0355 code and check for any other related codes. Visual Inspection: Check the ignition coil, its connectors, and wiring for any visible damages or signs of wear. Check the Wiring and Connector: Inspect for corroded terminals or damaged connectors. Ensure the wires are in the correct order if they’ve been tampered with. Test the Ignition Coil: Use a multimeter or oscilloscope to test the ignition coil’s functionality. Compare the waveform or readings to the manufacturer’s specifications. Swap Coils: If possible, swap the suspected faulty coil with a known working coil from another cylinder. If the fault code changes to the new cylinder, the coil is the issue. Check the PCM: In rare cases, the PCM might be the cause. Ensure it’s functioning correctly and isn’t sending incorrect signals to the ignition coil.

How to fix P0355 – learn from mechanics

I looked into P0355 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Mercedes

Vehicle Information

• 2006 Mercedes-Benz CLK350 3.5L

Issue + Repair History

• Intermittent CEL (Check Engine Light) and roughness.
• Previous repair: Replaced ignition coil and spark plug for cylinder #5 with OE MB parts. Cleared the fault code and did a rotor sensor adaption.
• Fault codes: 1019 (control line to ignition coil) and Po355 (ignition coil #5).

Suggestions from Community

• Move the new coil to another cylinder and check if the problem follows.
• Check the spark plugs from #5 and either replace or move them to another cylinder.
• Check for rodent damage to the wiring harness.
• Invest in a Mercedes SDS (Star Diagnostic System) for accurate diagnostics.
• Confirm the correlation between the scanner’s code description and the actual fault.

Final Fix

• The scanner’s code description was incorrect. The correct correlation was established between PO355 and 1019.
• Replaced coil #4 after confirming the scanner’s error.
• The vehicle has since covered 2,000 miles without any issues.

Case #2: Toyota

Vehicle Information

• 2006 Toyota RAV4 Sport 3.5L

Issue + Repair History

• Vehicle sets specific codes immediately after erasing.
• No drivability symptoms except cruise control being disabled due to the mentioned codes.
• Fault codes: P0301–306 (Misfires all cylinders), P0355, P1578, C1223, C1241, C1201.

Suggestions from Community

• Check the charging system and consider a potential issue with the ignition coil for cylinder 5.
• Inquire about any testing that has been done.
• Replace ignition coil for cylinder 5. One bad coil can affect others.
• Replace the brake light switch to address the ‘C’ codes.

Final Fix

• Replaced the coil for cylinder 5 and erased codes.
• After driving about 60 miles, no codes returned.
• Fixing the P0355 with the coil seemed to resolve all other codes.

Case #3: Ford

Vehicle Information

• 2006 Ford Five Hundred SEL 3.0L

Issue + Repair History

• Vehicle has a P0355 fault code.
• After clearing the ignition circuit malfunction, the vehicle runs well until the check engine light returns and it starts running rough again, specifically cylinder #5.
• Fault code: P0355.
• Recent engine tune performed.

Suggestions from Community

• Check the wires going from PCM to the ignition coil.
• Consider replacing the ignition coil or moving it to another cylinder.
• P0355 typically indicates a primary circuit in cylinder number 5 coil pack. If not addressed, it might damage the transistor in the PCM.
• Misfire might be due to the computer shutting power to the coil and fuel injector to prevent damage to the transistor.
• Swap the #5 ignition coil with another cylinder to see if the issue persists or follows the coil.
• Check pin fit and harness integrity at the #5 Ignition Coil connector.
• Use a Noid light plugged into the ignition coil connector to test for proper voltage and trigger signal from the PCM.

Final Fix

• Replaced 2 more ignition coils (one OEM and one from Carquest).
• Also changed the coil on cylinder #4.
• The check engine light has been off and the vehicle runs well.

Case #4: Volvo

Vehicle Information

• 1999 Volvo V70 2.4L

Issue + Repair History

• Vehicle stalls and has a slight rough idle when cold, lasting about 20-30 seconds.
• Fault codes: P1081 (unknown description), P0350 (ignition coil primary/secondary circuit malfunction), and P0355 (ignition coil e primary/secondary circuit malfunction).
• No information available on P1081.
• Issues with the scan tool (GENYSIS) showing incorrect PCM ID.

Suggestions from Community

• Ensure the car has Volvo spark plugs.
• Check cam or crank sensor.
• Check for vacuum leaks.
• Check the wires from PCM to ignition coil and consider replacing or moving the coil.
• Swap the #5 ignition coil with another cylinder to see if the issue persists or follows the coil.
• Check the charging system and consider a software upgrade for the throttle.
• Tighten the connection at the antenna ring for the ignition key or consider replacing the antenna ring.
• Check for oil in the plug wells and inspect the spark plugs.

Final Fix

• Replaced the #5 coil and installed a new set of spark plugs.
• Had the computer reflashed.
• After the repairs, the vehicle passed the North Carolina state inspection and has been running well.

Case #5: Honda

Vehicle Information

• 2002 Honda Civic EX 1.7L

Issue + Repair History

• Vehicle came in with a crank sensor code.
• Corroded terminals were found on the connector.
• The technician ordered new terminals but forgot the order of the wires.
• The wiring diagram only provided terminal numbers which weren’t on the connector.
• The technician connected the new terminals but the vehicle still showed codes.
• The technician verified power and ground to the connector but was uncertain about the signal wire’s correct terminal.

Suggestions from Community

• Clarification on the fault code, suggesting it might be P0335 (CKP sensor no signal) instead of P0355.
• The order of the wires in the connector:
  1. Blue (sensor output)
  2. Brown/Yellow (ground)
  3. Yellow/Black (circuit D04)
• A suggestion that there might be two problems, leading to the MIL light still being on.

Final Fix

• The crank sensor was found to be faulty.
• Corrosion was observed on the sensor’s terminal tabs.
• After replacing the crank sensor, a perfect waveform was observed.
• The technician confirmed that the original fault code should have been P0335.
• The bolt on the crank pulley posed some challenges during the repair.
• The technician thanked community members for their assistance, especially Edgar for verifying the wire order on an actual car.

How to diagnose P0355

I made you an overview of solving this DTC, based on all the advice that was suggested by certified mechanics to address this issue in previously mentioned service cases.

• Check the Wiring and Connector: In multiple cases, corroded terminals or connectors were identified as the root cause. Always inspect the wiring and connectors for any signs of damage or corrosion.
  
• Verify Wire Order: If connectors or terminals are replaced, ensure that the wires are placed in the correct order. If uncertain, consult a wiring diagram or seek advice from fellow technicians.
  
• Replace the Crank Sensor: If there are issues with the waveform or if corrosion is observed on the sensor’s terminals, consider replacing the crank sensor.
  
• Use Reliable Diagnostic Tools: Ensure that the diagnostic tools being used provide accurate and reliable information. Some technicians faced challenges due to misleading or incomplete data from their diagnostic tools.
  
• Consider Multiple Faults: If the issue persists after addressing the identified problem, consider the possibility of multiple faults or underlying issues that might be triggering the fault code.