P0354 on 2008-2012 Honda Accord: Ignition Coil 'D' (Cylinder 4) Causes and Fixes

What's Unique About the 2008-2012 Honda Accord

While a bad coil is the most common cause on all engines, the 3.5L V6 in this Accord generation has a well-documented issue with piston rings that can lead to excessive oil consumption and spark plug fouling. A Service Bulletin (13-078) was issued for misfire codes (P0301-P0304) related to this. A severely oil-fouled spark plug requires much higher voltage to create a spark, which can overwork and eventually damage the ignition coil, leading to the P0354 circuit code. Therefore, if you have a V6 with code P0354, it is critical to inspect the spark plug for heavy, black, oily deposits, as this underlying condition could be the root cause.

Symptoms You May Notice

• Check Engine Light is on (may be flashing)
• Engine misfiring or running rough, especially at idle
• Noticeable loss of power and sluggish acceleration
• Reduced fuel economy
• Hesitation or stumbling when accelerating
• Smell of unburnt fuel from the exhaust

Most Likely Causes

1. Faulty Ignition Coil on Cylinder #4 🔴 High Probability Ignition coils are wear-and-tear components that fail over time due to high heat and vibration. It is the most common reason for a P035x code on this platform.
   How to confirm: Perform a 'swap test'. Move the ignition coil from cylinder #4 to another cylinder (e.g., cylinder #3). Clear the codes and drive the vehicle. If the code returns as P0353, the ignition coil is confirmed to be faulty.
   Typical fix: Replace the faulty ignition coil. It is often recommended to replace the corresponding spark plug at the same time. Many owners on forums recommend using OEM brands like Denso, Hitachi, or NGK for reliability, as cheap aftermarket coils can fail prematurely.
   Est. part cost: $40-$90
2. Worn or Fouled Spark Plug in Cylinder #4 🟡 Medium Probability On V6 models, a known piston ring issue can cause oil to foul the spark plugs, leading to misfires and potentially damaging the ignition coil (see TSB 13-078). On all engines, spark plugs are a regular maintenance item that can fail with age.
   How to confirm: Remove the spark plug from cylinder #4. Inspect it for wear, damage, or fouling (especially black, oily deposits on V6 models). A healthy plug should have a light tan or grayish deposit.
   Typical fix: Replace the spark plug. If oil fouling is present on a V6, the underlying oil consumption issue should be investigated, which may require a PCM software update or more extensive engine repair as outlined in TSB 13-078.
   Est. part cost: $10-$25
3. Damaged Wiring or Connector ⚪ Low Probability Rodents are known to build nests under the engine cover and chew on the ignition coil wiring harnesses, causing an open or short circuit. The connector's plastic locking tab can also become brittle and break, leading to a loose connection.
   How to confirm: If the coil swap test does not move the code, visually inspect the wiring harness and connector for the cylinder #4 ignition coil. Look for any signs of breaks, corrosion, melting, loose pins, or chew marks. A 'wiggle test' on the harness with the engine running may cause the misfire to change, indicating a wiring issue.
   Typical fix: Repair the damaged section of wire or replace the connector pigtail. In a documented case on a 2021 Accord, rodent-damaged wires were soldered to fix a P0354 code.
   Est. part cost: $15-$40

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This is the least likely cause. A faulty coil driver circuit within the PCM can trigger this code. All other possibilities, especially coil, plug, and wiring, should be exhausted before considering PCM replacement, which requires professional diagnosis and programming.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0354 and check for any other codes like P0304.
2. Identify cylinder #4. For the 2.4L I4, it's the last one on the driver's side. For the 3.5L V6, it's the front-most cylinder in the bank near the radiator.
3. Swap the ignition coil from cylinder #4 with the coil from another cylinder (e.g., cylinder #3).
4. Clear the codes with the scanner and start the engine. Let it run and/or take a short drive.
5. Re-scan for codes. If the code is now P0353, the ignition coil you moved is bad and needs to be replaced.
6. If code P0354 returns, the coil is likely good. The problem is probably the spark plug or the wiring.
7. Turn off the engine and remove the ignition coil from cylinder #4 again. Remove the spark plug.
8. Inspect the spark plug for excessive wear, damage, or fouling (carbon or oil). If the plug is bad, replace it. On V6 models, oil fouling is a major red flag for the piston ring issue described in TSB 13-078.
9. If the plug and coil are good, carefully inspect the wiring connector and harness for cylinder #4's coil. Check for loose connections, corrosion, or damaged wires (chew marks from rodents are a possibility). Ensure the connector clicks securely into place.
10. When installing the new coil, apply a small amount of dielectric grease to the inside of the boot to protect against moisture and ensure a good seal on the spark plug.
11. If all of the above check out, the issue may be with the PCM, which requires professional diagnosis.

Parts You'll Likely Need

• Ignition Coil (for 2.4L 4-Cylinder) (OEM #30520-R40-007) — This is the most common failure part for code P0354 on the 4-cylinder model.
  Trusted brands: Hitachi (often OEM), Denso, NGK
  OEM price range: $70-$105
  Aftermarket price range: $40-$80
• Ignition Coil (for 3.5L V6) (OEM #30520-R70-A01 (may be superseded by 30520-R70-S01)) — This is the most common failure part for code P0354 on the V6 model.
  Trusted brands: Hitachi (often OEM), Denso, NGK
  OEM price range: $85-$125
  Aftermarket price range: $45-$90
• Spark Plug (for 2.4L 4-Cylinder) (OEM #Denso: SKJ20DR-M13 or NGK: ILZKR7B-11S) — Often replaced with the ignition coil as a set, or if it is found to be worn or fouled.
  Trusted brands: NGK, Denso
  OEM price range: $15-$25
  Aftermarket price range: $8-$18
• Spark Plug (for 3.5L V6) (OEM #Denso: SKJ20DR-M11 or NGK: IZFR6K-11) — Often replaced with the ignition coil. Crucial to inspect and replace if oil-fouled due to the known piston ring issue.
  Trusted brands: NGK, Denso
  OEM price range: $15-$25
  Aftermarket price range: $8-$18

Related Codes That Often Appear With This One

• P0304 — P0304 means 'Cylinder 4 Misfire Detected'. Since the P0354 code indicates a problem with the component that creates the spark for cylinder 4, it is very common for the computer to also detect the resulting misfire.
• P0301, P0302, P0303 — On V6 models, if the oil consumption issue is severe, it's possible to see misfire codes on other cylinders covered by TSB 13-078 (cylinders 1-4) in addition to the P0354 circuit code.

Technical Service Bulletins (TSBs) & Recalls

• 13-078 - Warranty Extension: MIL Comes On with DTCs P0301 thru P0304

Platform-Specific Known Issues

• Honda Service Bulletin 13-078 addresses a warranty extension for 2008-2012 Accord V6 models due to a class-action lawsuit. The issue involves piston rings on cylinders 1-4 rotating and aligning, causing excessive oil consumption and spark plug fouling, which leads to misfire DTCs (P0301-P0304). A severely fouled plug can damage the ignition coil, triggering P0354. The fix involves a PCM software update for 2008-11 models, and if the problem persists or for 2012 models, cleaning pistons and replacing the piston rings.

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Winding Resistance — expected: 0.49 - 0.57 Ohms. Failure: A reading of OL (Open Loop/infinity) or significantly outside this range indicates a faulty coil.
• Ignition Coil Secondary Winding Resistance — expected: 9.5 - 11.1 kOhms (kilo-ohms). Failure: A reading of OL (Open Loop/infinity) or significantly outside this range indicates a faulty coil.
• Ignition Coil Connector - Power Wire Voltage — expected: Battery Voltage (approx. 12V) with Key On, Engine Off.. Failure: 0V or low voltage indicates a problem with the power supply from the main relay or a break in the wire.
• Ignition Coil Connector - Ground Wire Resistance — expected: Less than 1 Ohm to a known good chassis ground.. Failure: High resistance or OL indicates a bad ground connection, which is critical for coil operation.
• Ignition Coil Connector - Signal Wire Frequency (Advanced) — expected: 5 - 20 Hz on a multimeter's frequency (Hz) setting while the engine is idling.. Failure: A reading of 0 Hz or an erratic signal points to a problem with the trigger signal from the PCM or a break in the signal wire.

Scan Tool Commands That Help

• Honda HDS (or advanced aftermarket scanner): Coil Driver Test / Actuator Test — After confirming power and ground are good at the coil connector, this command forces the PCM to send a trigger signal to the coil. It can be used with a test light or scope on the signal wire to confirm the PCM driver and wiring integrity without the engine running.
• Honda HDS: ALL INJECTORS STOP — This is a related diagnostic function that can be used to isolate systems. While not directly for testing the coil circuit, it demonstrates the type of bidirectional control available in the dealer-level software to aid in complex diagnostics.

Wiring & Ground Locations

• G101 (Main Engine/PCM Ground) — On the driver's side of the engine bay, typically bolted to the intake manifold or thermostat housing. It is a collection of ground wires consolidated to a single bolt-down point.. This is the primary ground reference for the PCM and the entire engine sensor network. A loose or corroded G101 can cause erratic behavior across the ignition system, leading to intermittent misfires and codes like P0354 that are difficult to diagnose.
• Cylinder 4 Ignition Coil Connector — Plugged directly into the top of the ignition coil for cylinder #4.. This 3-pin connector provides the coil with power, ground, and the trigger signal from the PCM. The pins are typically: Pin 1 - Signal (IGT) from PCM; Pin 2 - Ground; Pin 3 - 12V+ Power (Key On). Wire colors must be verified, but are often Black/Yellow (Power), Black (Ground), and a third color for the signal. A fault in this connector or its wiring is a direct cause of P0354.

Real Owner Repair Stories

• Reddit user on r/autorepair (Mazda 3 (similar coil-on-plug system)) — Check Engine Light with code P0354. Car ran fine with maybe slightly weaker acceleration.
  ❌ Tried (didn't work) Replaced the ignition coil for cylinder 4., Replaced the spark plug for cylinder 4., Cleared the code, but it returned.
  ✅ What actually fixed it The final fix was not posted by the user, but the top-voted advice from technicians was to address a likely wiring or connector issue. The recommendation was to use a small tool to slightly twist the female pins inside the plastic connector to increase their tension on the male pins of the new ignition coil, as loose pin fitment is a common cause for the code to return after parts replacement.

OEM Part Supersession History

• 30520-R70-A01 → 30520-R70-S01 — Standard part revision by the manufacturer, likely for improved reliability or a change in supplier.
  Heads up: The new part number (30520-R70-S01) is a direct replacement for the old one and is fully compatible with all 3.5L V6 models in this generation.

Diagnostic Flowchart

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: A used part is a reasonable choice for a wiring harness connector pigtail if the original is broken or corroded. You can splice a used connector from a junkyard harness to save money over buying a new harness section. A complete used engine wiring harness is also a viable option if multiple connectors or wires are damaged by rodents.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For a connector pigtail, ensure the plastic is not brittle and the locking tab is intact.
• Check that the wire insulation is flexible and not cracked.
• Look for any signs of corrosion (green or white powder) on the metal pins inside the connector.
• If buying a full harness, ensure it came from a vehicle with no signs of engine fire or flood damage.

OEM-only on this vehicle (don't cheap out):

• Ignition Coils
• Spark Plugs

Aftermarket brands forum-validated for this vehicle:

• Hitachi (often the Original Equipment Manufacturer)
• Denso
• NGK
• Delphi

Brands owners have reported issues with on this vehicle:

• Unbranded, no-name ignition coils sold on marketplaces like Amazon or eBay are frequently reported on forums to fail prematurely, sometimes within weeks or months, causing the code to return.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P0304 — Cylinder #4 Misfire Detected. This is the most common companion code, as the ignition coil circuit failure described by P0354 directly causes a misfire in that cylinder.
• P0353 — Ignition Coil 'C' Primary/Secondary Circuit. This code for cylinder #3 is a key diagnostic indicator. If it appears after swapping the coil from cylinder #4 to cylinder #3, it confirms the original coil is faulty.
• P0301 — Cylinder #1 Misfire Detected. On V6 models, TSB 13-078 notes an oil consumption issue affecting cylinders 1-4. The presence of P0354 could be related to this larger problem causing misfires in other cylinders like P0301.
• P0356 — Ignition Coil 'F' Primary/Secondary Circuit. The appearance of other P035x codes alongside P0354 can indicate that multiple coils are failing due to age or a widespread wiring harness issue.
• P0300 — Random/Multiple Cylinder Misfire Detected. If multiple ignition coils are failing around the same time, this code may appear along with specific circuit codes like P0354 to indicate a more widespread misfire condition.

Frequently Asked Questions