P0354 on 2005-2010 Lexus RX 3.5L: Ignition Coil 'D' Circuit Causes and Fixes

What's Unique About the 2005-2010 Lexus RX

Ignition coil failure is a well-documented, common issue on the 2GR-FE V6 engine used across many Toyota and Lexus models from this era, including the RX. The problem became frequent enough that Toyota and Lexus issued updated ignition coil designs to improve durability. Fortunately for owners, the cylinders are numbered 2, 4, 6 from passenger to driver side on the front bank (closest to the radiator) and 1, 3, 5 on the rear bank (against the firewall). Cylinder #4 is located in the front cylinder bank, making it significantly easier to access and replace than the coils on the rear bank, which require removing the intake manifold.

Symptoms You May Notice

• Check Engine Light is on
• VSC (Vehicle Stability Control) light may also illuminate
• Engine running rough or shaking, especially at idle
• Engine hesitation or stumbling during acceleration
• Reduced engine power
• Potential for the engine to have trouble starting

Most Likely Causes

1. Failed Ignition Coil 🔴 High Probability This is a very common failure item on the 2GR-FE engine. Toyota released updated parts to address the frequency of these failures.
   How to confirm: Swap the ignition coil from cylinder #4 (front bank, middle) with the coil from cylinder #2 or #6 (the other front bank cylinders). Clear the codes and drive the vehicle. If the code changes to P0352 or P0356 respectively, the coil is confirmed bad.
   Typical fix: Replace the faulty ignition coil with a new one. It is held in by a single 10mm bolt.
   Est. part cost: $50-$130
2. Worn or Fouled Spark Plug 🟡 Medium Probability A worn-out spark plug with a large gap can put extra strain on the ignition coil, potentially causing it to fail. While less likely to be the direct cause of the P0354 circuit code, it's a common contributing factor and should be inspected.
   How to confirm: After removing the ignition coil, remove the spark plug from cylinder #4. Inspect it for excessive wear, oil or carbon fouling, or a cracked insulator. The recommended gap for a new plug is 1.0-1.1mm.
   Typical fix: Replace the spark plug. It is recommended to replace all six spark plugs if they are near their service interval (typically 60,000-120,000 miles for iridium plugs).
   Est. part cost: $15-$30 per plug
3. Damaged Wiring or Connector ⚪ Low Probability
   How to confirm: Visually inspect the wiring harness and connector for cylinder #4's ignition coil. Look for any signs of cracking, melting, corrosion on the pins, or loose connections. With the ignition ON and engine OFF, use a multimeter to check for 12V power at the specified pin on the connector. 🎬 See how to diagnose a chewed wiring harness issue
   Typical fix: Repair the damaged section of the wiring harness or replace the connector pigtail.
   Est. part cost: $10-$30 for a connector

Rare But Worth Checking

• Faulty Engine Control Module (ECM): This is very rare. A Toyota TSB (TSB-0047-10) mentions the ECM as a potential, though unlikely, cause for this series of codes. All other possibilities, especially the coil and wiring, should be exhaustively ruled out before considering ECM replacement.

Diagnosis Steps

1. Read the trouble codes with an OBD-II scanner to confirm P0354 is present. Note any other codes, such as P0304.
2. Remove the plastic engine cover by pulling it straight up.
3. Locate the ignition coils on the front cylinder bank (closest to the radiator). Cylinder #4 is the middle one.
4. Swap the ignition coil from cylinder #4 with the coil from cylinder #6 (front, driver's side). The coils are identical.
5. Clear the trouble codes with the scanner.
6. Start the engine and let it run for a minute, then re-scan for codes. If the code has changed to P0356, the ignition coil is faulty and must be replaced.
7. If the code remains P0354, the issue is likely with the wiring or spark plug for cylinder #4. Swap the coils back to their original positions.
8. Disconnect the connector for the cylinder #4 coil. Inspect the connector and harness for any visible damage, corrosion, or loose pins.
9. If the wiring looks good, remove the ignition coil and then the spark plug. Inspect the spark plug for wear, damage, or fouling. Replace if it is in poor condition or past its service interval.
10. If the spark plug is good, you can test the wiring. With the key on (engine off), use a multimeter to check for 12V power at the appropriate pin on the harness connector.

Parts You'll Likely Need

• Ignition Coil (OEM #90919-A2007) — This is the most common failure part for a P0354 code on this engine. This is the latest updated part number from Toyota/Lexus, superseding 90919-A2004 and others.
  Trusted brands: Denso (OEM, Part No. 673-1309), NGK, Delphi, Beck/Arnley
  OEM price range: $90-$130
  Aftermarket price range: $50-$90
• Iridium Spark Plug (OEM #90919-01233) — It is wise to replace the spark plug at the same time as the coil, as a worn plug can cause a new coil to fail prematurely.
  Trusted brands: Denso, NGK
  OEM price range: $20-$30
  Aftermarket price range: $15-$25

Related Codes That Often Appear With This One

• P0304 — P0304 means 'Cylinder 4 Misfire Detected'. P0354 is the more specific code that identifies the electrical fault in the ignition coil circuit as the *cause* of the misfire that P0304 reports.
• P0300 — This code for 'Random/Multiple Cylinder Misfire' can appear if the misfire from cylinder 4 is severe or intermittent, causing the crankshaft speed to fluctuate in a way the ECM interprets as multiple misfires.

Technical Service Bulletins (TSBs) & Recalls

• TSB-0047-10: Mentions that some 2GR-FE equipped vehicles may exhibit a MIL ON with codes P0351-P0356, and that the cause could be a faulty coil or, rarely, the ECM.
• L-SB-0045-12 Rev: While for the RX 450h hybrid model, this TSB addresses misfire codes (P0300-P0306) on the 2GR platform and points to issues that can go beyond simple ignition components, sometimes involving fuel injectors or ECM software for rough running on a cold start.

Platform-Specific Known Issues

• Real-World Repair Story: A user on ClubLexus with a 2007 RX350 reported getting the P0354 code along with VSC and Check Engine lights. After confirming the code, they ordered a Beck Arnley ignition coil (part 178-8311) from Amazon for $45. The user noted that the part that arrived appeared to be a genuine OEM part with a Toyota stamping. They successfully replaced the coil themselves, noting the only tricky part was releasing the electrical connector clip.
🎬 Watch: Step-by-step ignition coil replacement walkthrough

Mechanic-Grade Diagnostic Values

• Ignition Coil Primary Winding Resistance — expected: 0.5 to 2.0 Ohms. Failure: A reading outside of this range (e.g., an open circuit or a dead short) indicates a failed coil.
• Ignition Coil Connector Power Supply — expected: 12V+ (Battery Voltage) at Pin 1 with Key On, Engine Off. Failure: No voltage indicates a problem with the power supply circuit, fuse, or ignition relay, not the coil itself.
• System Voltage — expected: Greater than or equal to 12.6V with engine off; 13.5V or higher with engine running.. Failure: Low system voltage can cause various electrical issues, including stress on ignition components, and should be corrected before diagnosing individual parts.

Hidden / Shadow Codes Worth Checking

• Mode 6, Test ID $0A, Component ID $04: This is not a 'code' but a data parameter within an advanced scan tool. It allows a technician to view the raw misfire count for cylinder #4 since the last time codes were cleared. This can confirm if the P0354 circuit fault is causing an actual, countable misfire, even if it's not yet severe enough to set a P0304 code. (see via Professional scan tool or specific OBD-II apps (like Torque Pro with custom PIDs) that can access Mode 6 data. Toyota's Techstream software provides the most reliable access.)

Scan Tool Commands That Help

• Toyota Techstream: Live Data -> Misfire Count (Cylinder 4) — Use this to confirm in real-time that the electrical fault of P0354 is causing a physical misfire. Watching the counter for cylinder #4 increment validates the symptom and isolates the issue.
• Toyota Techstream: Active Test -> Control the Injection OFF (Cylinder 4) — After confirming P0354, this test verifies if the ECM has initiated its catalyst-protection strategy by cutting fuel to cylinder #4. If the injector is off during normal running, it confirms the ECM is actively responding to the P0354 fault.

Wiring & Ground Locations

• Ignition Coils 2, 4, 6 (Front Bank) — Located on top of the left (front) valve cover, easily accessible after removing the plastic engine cover.. This is the physical location of the coil for cylinder #4. Knowing its exact position between #2 and #6 is critical for testing, swapping, and replacement.
• Ignition Coil Connector (Cylinder 4) — The 4-pin electrical connector that plugs directly into the top of the ignition coil for cylinder #4.. The connector itself or its wiring is the second most likely point of failure after the coil. The plastic locking tab can become brittle and break, leading to a poor connection. A P0354 code without a corresponding P0304 misfire code is a strong indicator of a connector or wiring issue.
• Ignition Noise Filter — There are two noise filters for the ignition system. The one for the front bank is located on the top left side of the engine.. While a rare point of failure, this component is part of the ignition coil circuit and could theoretically cause issues if it failed.

Real Owner Repair Stories

• ClubLexus Forum user 'Luv07RX350' (2007 Lexus RX350 with ~99k miles) — Engine stuttering, Check Engine light on, VSC light on. Scanned codes and found P0354 'Confirmed' and P0300-P0306 as 'Pending'.
  ❌ Tried (didn't work) Initially reset the codes, but the user's plan was to proceed with diagnostics if the light returned.
  ✅ What actually fixed it The user confirmed the standard, correct diagnostic procedure: swap the ignition coil from cylinder #4 with the one from cylinder #6. If the code changes to P0356, the coil is bad and needs replacement. This is the universally accepted fix for this issue.

OEM Part Supersession History

• 90919-A2004 → 90919-A2007 — Part update by Toyota/Lexus to improve durability and address common failures.
• 90919-A2007 → 90919-A2013 — Further revision and consolidation of the part by the manufacturer.
  Heads up: All previous part numbers (90919-A2004, 90919-A2007, 90919-02251, 90919-A2002) are replaced by 90919-A2013. When ordering, this is the number to use.

Model Year Variations Within This Range

• 2005-2006: The 2005-2006 Lexus RX was the RX330 model and used the 3MZ-FE 3.3L V6 engine. While it can experience similar codes, the parts and specific procedures may differ. This guide is specific to the 2GR-FE 3.5L V6 found in the 2007-2010 RX350 models.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Rupturing VVT-i Oil Supply Hose 🔴 High — Common on 2007-2009 models. The original rubber hose section degrades and can burst without warning, leading to rapid oil loss and catastrophic engine failure if not shut down immediately. (Ref: Limited Service Campaign (LSC) issued by Toyota/Lexus to replace the rubber hose with an all-metal line (Part No. 15772-31030).)
• Timing Cover Oil Leak 🟠 Medium — A well-documented issue where the sealant on the timing chain cover fails, causing a significant oil leak. Typically occurs between 60,000 and 100,000 miles.
• Power Steering Rack Leaks 🟠 Medium — Leaks from the rack and pinion assembly were common, particularly on 2007-2008 models, often requiring replacement of the entire assembly.
• Cracked Dashboard 🟡 Low — Very common on 2007-2008 models. The dashboard material becomes brittle and cracks, especially with sun exposure. (Ref: Lexus offered an extended warranty/recall program to replace the dashboards, but it has since expired.)
• Transmission Shifting Issues 🟠 Medium — Some owners, particularly of the 2010 model, report hesitation, delays, or rough shifting, especially at low speeds or when shifting between reverse and drive.

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For an ignition coil on a 2GR-FE engine, buying a used part from a junkyard is NOT recommended. This is a known high-failure-rate component, and a used coil is likely to have significant wear and a short remaining lifespan.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• Check for cracks in the plastic housing.
• Ensure the electrical connector pins are clean and free of corrosion.
• Avoid any coils that have signs of oil contamination on the boot.
• If possible, ask for the donor vehicle's mileage; lower is always better.

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

• Ignition Coil

Aftermarket brands forum-validated for this vehicle:

• Denso (This is the Original Equipment Manufacturer, part number 673-1309 is the direct equivalent to the Toyota part).
• NGK

Brands owners have reported issues with on this vehicle:

• Unbranded, low-cost ignition coils from online marketplaces like Amazon or eBay. Forum users frequently warn about counterfeit Denso parts being sold, which often fail prematurely. It is safer to buy from a reputable auto parts store or an authorized Denso dealer.

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 — This is a cylinder-specific misfire code for cylinder #4 that often appears alongside the P0354 ignition circuit code.
• P0352 — Represents an ignition coil circuit issue on cylinder #2; often seen if a faulty coil is swapped from cylinder #4 to #2 during diagnosis.
• P0356 — Represents an ignition coil circuit issue on cylinder #6; often seen if a faulty coil is swapped from cylinder #4 to #6 during diagnosis.
• P0351-P0356 — A series of codes cited in TSB-0047-10 relating to faulty ignition coils or ECM issues on the 2GR-FE engine.
• P0300-P0306 — General misfire codes addressed in L-SB-0045-12 Rev for the 2GR platform, which can be related to ignition components, fuel injectors, or ECM software.

Frequently Asked Questions