P0301 on 2017-2019 Honda Ridgeline: Cylinder 1 Misfire Causes and Fixes

What's Unique About the 2017-2019 Honda RIDGELINE

The 3.5L direct-injection V6 engine (J35Y6) in the second-generation Ridgeline is known for a specific issue causing misfire codes, including P0301. Honda issued TSB 21-010, which states that debris from the manufacturing process of the high-pressure fuel pump or the fuel injectors themselves can cause them to clog or wear internally. This leads directly to misfires and is a well-documented problem for this specific engine platform, also affecting the Honda Pilot, Odyssey, and some Acura models with the same engine. Because of this known defect, a P0301 code has a very high probability of being the fuel injector.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on or flashing
• Rough or shaky idle
• Hesitation or stumbling during acceleration
• Noticeable loss of engine power
• Reduced fuel economy
• Smell of gasoline from the exhaust
• Engine vibration or shudder, especially in ECO mode

Most Likely Causes

1. Faulty or Clogged Fuel Injectors 🔴 High Probability → Shop Fuel Injector Honda TSB 21-010 explicitly identifies debris from the fuel system manufacturing process as a cause for injector failure on this platform, leading to misfires. This is the most likely cause and is covered by a 10-year/150,000-mile warranty extension.
   How to confirm: The definitive confirmation is to have a Honda dealer check your VIN for warranty eligibility. A technician can also perform a 'Cylinder AF Test' using the Honda Diagnostic System (HDS). A DIY method is to swap the cylinder 1 injector with another cylinder's injector (e.g., cylinder 2) and see if the misfire code changes to P0302. This is a labor-intensive task.
   Typical fix: Replace all six fuel injectors with the updated kit 🎬 Watch: Step-by-step Honda 3.5L fuel injector replacement guide (part number 16010-RLV-315) as recommended by Honda's service bulletin. While only one may be failing, others are likely contaminated and will fail soon. This repair is often covered free of charge under the warranty extension.
   Est. part cost: $250-$400 for a set of OEM injectors (16010-RLV-315).
2. Worn or Fouled Spark Plug 🟡 Medium Probability → Shop Spark Plug Spark plugs are a regular maintenance item. While durable, they can fail or become fouled by oil or carbon. Issues related to the VCM system can sometimes accelerate spark plug fouling on deactivated cylinders, though this is less common on this refined engine version.
   How to confirm: Remove the spark plug from cylinder 1 and inspect it for wear (worn electrode), damage (cracked porcelain), or fouling (black, oily, or white deposits). Compare it to a new plug. A fouled plug can be moved to another cylinder to see if the misfire follows.
   Typical fix: Replace the spark plug. The OEM plug is typically an NGK Laser Iridium, part number DILKAR7L11 (or NGK stock number 94124). It is best practice to replace all six spark plugs at the same time.
   Est. part cost: $20-$30 per plug.
3. Failed Ignition Coil 🟡 Medium Probability → Shop Ignition Coil Ignition coils can fail from heat and vibration over time, leading to a weak or non-existent spark. It's a common failure point on most modern engines.
   How to confirm: The easiest way to confirm a bad coil is to swap 🎬 See how to diagnose and fix a P0301 misfire code the ignition coil from cylinder 1 with another cylinder (e.g., cylinder 2). Clear the codes and drive the vehicle. If the code returns as P0302, the coil is faulty.
   Typical fix: Replace the failed ignition coil. It's a simple, single-component replacement. The OEM part number is typically 30520-RLV-A01.
   Est. part cost: $50-$100 for one OEM-quality coil from brands like Denso or Hitachi.

Rare But Worth Checking

• VCM (Variable Cylinder Management) Issues: While Honda's VCM system is intended to save fuel by deactivating cylinders, it can contribute to spark plug fouling due to oil being sucked past the piston rings on the deactivated cylinders. This is a known issue on J-series engines. Some owners install a 'VCM Muzzler' or 'VCM Tuner' to disable the system as a preventative measure, though its direct link to the P0301 injector issue on this specific model is secondary to the TSB.
• Low Engine Compression: Internal engine problems like a worn piston ring, leaking valve, or a bad head gasket can cause a loss of compression, leading to a misfire. This is a more serious mechanical issue and requires a compression test to diagnose. This is an unlikely cause unless the vehicle has very high mileage or has been severely overheated.

Diagnosis Steps

1. Contact a Honda Dealer First: Before any other step, call a Honda service center with your Vehicle Identification Number (VIN). Ask them to check for eligibility under the warranty extension for fuel injectors (Service Bulletin 21-010). This is the most probable cause and the repair may be free.
2. Read All Codes: Use an OBD-II scanner to confirm P0301 and check for any other pending or stored codes. The presence of P030x, P219A/B, or P0420/P0430 strongly suggests the injector issue.
3. Swap the Ignition Coil: If not covered by warranty or you wish to diagnose further, swap the ignition coil from cylinder 1 with cylinder 2. Clear the codes and drive. If the code changes to P0302, the ignition coil is bad.
4. Inspect the Spark Plug: If the coil is good, remove the spark plug from cylinder 1. Inspect it for wear, damage, or fouling. 🎬 Watch: How to fix misfire codes using basic hand tools If it looks bad, replace it (OEM part is NGK DILKAR7L11).
5. Suspect the Fuel Injector: If the spark and ignition components are good, the fuel injector is the next logical suspect. This is a more involved job. A professional diagnosis or swapping the injector to another cylinder would confirm the failure.
6. Perform a Compression Test: If all else fails, a mechanical issue is possible. A compression test will check for issues with piston rings, valves, or the head gasket. This is an unlikely scenario.

Parts You'll Likely Need

• Fuel Injector Kit (Set of 6) (OEM #16010-RLV-315) — This is the most probable cause according to Honda's own service bulletin (21-010) for misfires on this vehicle. The kit includes all 6 injectors and is the official fix.
  Trusted brands: Honda OE
  OEM price range: $250-$400 (set)
  Aftermarket price range: $200-$350 (set)
• Ignition Coil (OEM #30520-RLV-A01) — A common failure point for any modern engine that directly causes a misfire on a single cylinder.
  Trusted brands: Denso, NGK, Hitachi
  OEM price range: $70-$100
  Aftermarket price range: $40-$70
• Spark Plug (OEM #NGK DILKAR7L11 (94124)) — A fouled or worn spark plug is a common cause of a misfire and is a standard maintenance item.
  Trusted brands: NGK, Denso
  OEM price range: $20-$30
  Aftermarket price range: $10-$20

Related Codes That Often Appear With This One

• P0300 — This is a random/multiple cylinder misfire code. It may appear with P0301 if the misfire is intermittent or starting to affect other cylinders due to the systemic fuel injector issue.
• P0302, P0303, P0304, P0305, P0306 — These codes indicate misfires in other cylinders. Seeing them alongside P0301 strongly points to a common cause like the fuel injectors, as noted in TSB 21-010.
• P219A / P219B — These codes indicate an air-fuel ratio imbalance between cylinders. They are specifically mentioned in TSB 21-010 as being directly related to the faulty fuel injector issue and are a strong indicator that the injectors are the root cause.
• P0420 / P0430 — These codes for catalyst efficiency below threshold can appear as a consequence of prolonged misfiring. Unburned fuel damages the catalytic converter. TSB 21-010 also includes these codes as part of the warranty extension.

Technical Service Bulletins (TSBs) & Recalls

• 21-010: Warranty Extension: MIL Comes On with DTC P0420/P0430, P030x, and/or P219A/B (Without Software Update). (Supersedes A18-025).
• A18-025: MIL Comes On with DTC P0300-P0306 or P219A/B. (Now superseded by 21-010).

Platform-Specific Known Issues

• Honda issued Technical Service Bulletin 21-010, which supersedes A18-025, for 2017-2019 Ridgelines experiencing misfire codes (P0301-P0306) and/or related codes (P219A/B, P0420/P0430). The cause is identified as potential clogging or internal wear in

Mechanic-Grade Diagnostic Values

• Fuel Pressure (at idle) — expected: 57-64 psi (390-440 kPa). Failure: Pressure significantly below this range indicates a problem with the fuel pump or regulator.
• Ignition Coil Primary Winding Resistance — expected: 0.49 - 0.57 Ω. Failure: A reading outside this range suggests a faulty coil.
• Ignition Coil Secondary Winding Resistance — expected: 9.5 - 11.1 kΩ. Failure: A reading outside this range suggests a faulty coil.

Hidden / Shadow Codes Worth Checking

• P219A / P219B: Air-Fuel Ratio Variation of Cylinder (Bank 1 / Bank 2). While not truly 'hidden,' these codes are specifically called out in Honda's TSBs as being directly related to the fuel injector problem. Their presence alongside a P0301 strongly confirms the injectors are the likely cause. (see via Standard OBD-II scanner.)

Scan Tool Commands That Help

• Honda Diagnostic System (HDS): Cylinder AF Test — This is a specific function mentioned in Honda TSBs 21-010 and 19-073. It is used to test the air-fuel ratio of individual cylinders to confirm a fuel injector malfunction, especially when only catalyst codes like P0420/P0430 are present without a misfire code.

Wiring & Ground Locations

• User-Added Grounding Post — There is a pre-threaded (M6x1) but unused hole in the chassis frame to the right of the airbox, near the fender. Many owners install a 40mm M6 bolt here to create an accessible grounding point for jump-starting or testing, as the factory ground point is obscured by the air intake.. Provides a reliable and accessible ground point for performing electrical tests on the ignition and fuel systems without having to disassemble the air intake to reach the battery's negative terminal.

Real Owner Repair Stories

• Reddit user in r/hondaridgeline (2019 Honda Ridgeline, 42,000 miles) — Emissions system light came on and off intermittently.
  ❌ Tried (didn't work) Initial dealer visit suggested it was a loose gas cap., Dealer initially denied warranty coverage for the fuel injectors, stating the VIN was not covered and quoting $1400 for the repair.
  ✅ What actually fixed it After the owner persisted, the fuel injector replacement was covered under the emissions warranty. The owner got the truck back with the issue resolved at no cost.
• CarComplaints.com user report (2019 Honda Ridgeline, 70,405 miles) — Check Engine Light and misfire symptoms.
  ❌ Tried (didn't work) Hoping for warranty coverage.
  ✅ What actually fixed it The fuel injectors were replaced at a cost of $1,148. The owner noted that this is a known problem but their specific VIN was not included in the warranty extension, forcing them to pay out-of-pocket.

OEM Part Supersession History

• 16010-RLV-305 (Injectors) → 16010-RLV-315 (Injectors) — The original injectors were prone to clogging or internal wear from debris originating from the high-pressure fuel pump or the injector manufacturing process itself, as documented in Honda TSBs.
  Heads up: The full repair kit specified in TSB 21-010 is part number 06160-RLV-305, which includes the updated injectors (16010-RLV-315) plus necessary gaskets and seals.

Model Year Variations Within This Range

• 2017-2019: These models are equipped with a 6-speed automatic transmission. The 9-speed ZF automatic was introduced for the 2020 model year. While not directly causing the P0301, it's a major powertrain difference.
• 2017-2019: According to TSB 21-010, vehicles in this range that require the fuel injector replacement do NOT need a corresponding PCM software update. This differs from some earlier 2016-2017 Honda Pilot models with the same engine that did require a software update as part of the same injector-related repair.