P0300 on 2022-2023 Infiniti QX60: Random Misfire Causes and Fixes

What's Unique About the 2022-2023 Infiniti QX60

The 2022-2023 QX60 uses a 3.5L direct-injection V6 (VQ35DD). For this specific generation, Infiniti has issued two key Technical Service Bulletins. TSB ITB22-030 addresses false P0300 codes that may appear during a cold start warm-up cycle on 2022 models, with no actual drivability issue present. More recently, TSB ITB23-026 was released for 2022-2023 models, also for a P0300 code, which may require reprogramming the ECM and, on 2023 models, the Transmission Control Module (TCM) as well. This makes a software update a critical first diagnostic step before pursuing mechanical repairs.

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 unstable idle
• Engine hesitation or stumbling during acceleration
• Reduced engine power
• Difficulty starting the engine
• Noticeable decrease in fuel economy
• A smell of raw fuel from the exhaust
• Engine stalls after driving for 30+ minutes and then refuses to restart until it cools down

Most Likely Causes

1. ECM/TCM Software Calibration Issue 🔴 High Probability Specifically addressed by Infiniti for 2022-2023 models. TSB ITB22-030 notes that misfire codes can be stored during a cold start warm-up cycle on 2022 models. TSB ITB23-026 is a broader bulletin for 2022-2023 models with P0300 that also directs technicians to reprogram the ECM and potentially the TCM.
   How to confirm: Check if the code appears primarily during or shortly after a cold start (for ITB22-030). An Infiniti dealer can check the vehicle's service history and current control module software part numbers against the TSBs.
   Typical fix: Reprogram the Engine Control Module (ECM) and/or Transmission Control Module (TCM) with updated software. This must be done by an Infiniti dealer or a qualified shop with access to Infiniti's CONSULT-III plus diagnostic tool.
   Est. part cost: $0-$250 (Cost is for labor if out of warranty; no parts are replaced)
2. Worn or Fouled Spark Plugs 🔴 High Probability → Shop Spark Plug Spark plugs are a standard wear item. On direct-injection engines, they can be susceptible to fouling. Some VQ-series engines have been noted to have oil consumption issues which can foul plugs prematurely. 🎬 Watch: How oil consumption can cause a P0300 misfire.
   How to confirm: Remove the spark plugs and inspect them for wear on the electrode, carbon buildup, oil fouling, or cracks in the porcelain. The service interval for iridium plugs is typically around 100,000 miles, but they can fail sooner.
   Typical fix: Replace all six spark plugs as a set. It is critical to use the correct OEM-spec iridium plugs, such as Infiniti part # 22401-EW61C. 🎬 See this walkthrough for replacing spark plugs on the 3.5L.
   Est. part cost: $60-$150
3. Faulty Ignition Coil(s) 🟡 Medium Probability → Shop Ignition Coil Ignition coils can fail from heat and age. While one failing coil usually triggers a specific cylinder code (e.g., P0301), a weak or intermittently failing coil can contribute to a random misfire code before it fails completely.
   How to confirm: If you have a specific cylinder code (e.g., P0302) along with P0300, swap the ignition coil from the misfiring cylinder with one from a known good cylinder. Clear the codes and see if the misfire code follows the coil (e.g., changes to P0304).
   Typical fix: Replace the faulty ignition coil. Many mechanics recommend replacing them as a set if they are original and the vehicle has high mileage. The OEM coil is often made by Hitachi. A common OEM part number is 22448-JA11C.
   Est. part cost: $50-$120 per coil
4. Vacuum Leak ⚪ Low Probability
   How to confirm: Visually inspect all vacuum hoses for cracks or disconnection. Check the intake manifold gaskets for leaks. A professional can perform a smoke test, which feeds smoke into the intake system to reveal the location of any leaks.
   Typical fix: Replace the cracked hose or leaking gasket.
   Est. part cost: $10-$300 (depending on the part)
5. Clogged or Faulty Fuel Injectors ⚪ Low Probability → Shop Fuel Injector The VQ35DD uses high-pressure direct injectors which can be sensitive to fuel quality. A stuck-open injector can flood a cylinder, causing a misfire and a strong fuel smell.
   How to confirm: This requires professional diagnosis, including a fuel injector balance test or checking individual injector performance with a capable scan tool. A strong smell of raw fuel is a key indicator of a stuck-open injector.
   Typical fix: Professionally clean the injectors or replace the faulty injector(s). On the QX60, injectors are typically sold as a complete fuel rail assembly.
   Est. part cost: $150-$400 per injector

Rare But Worth Checking

• Faulty Crankshaft or Camshaft Position Sensor: → Shop Engine Crankshaft A failing crank or cam sensor can provide erratic data to the ECM, disrupting ignition and valve timing and causing random misfires. Symptoms can include stalling when the engine is hot followed by a no-start condition until it cools. This was the confirmed fix for a QX60 with these exact symptoms.
• Low Fuel Pressure: A weak fuel pump or clogged fuel filter can starve the engine of fuel, leading to lean misfires across all cylinders, especially under load. The VQ35DD has both a low-pressure in-tank pump and a high-pressure mechanical pump; either can be a point of failure.
• Intake Valve Carbon Buildup: As a direct-injection (DI) engine, the VQ35DD does not spray fuel over the back of the intake valves. This can lead to carbon deposits accumulating on the valves over time, which can disrupt airflow into the cylinders and cause misfires. This is a known long-term maintenance consideration for all DI engines.
• Faulty EVAP Purge Valve: → Shop Vapor Canister A purge valve that is stuck open can create a vacuum leak, and in some cases, allow fuel vapors to enter the intake manifold at the wrong time, such as immediately after refueling. This can cause a temporary rich condition and trigger a P0300 code.

Diagnosis Steps

1. Read all stored fault codes with an OBD-II scanner. Note any codes accompanying P0300, such as P0301-P0306.
2. (2022-2023 Models Especially) Check with an Infiniti dealer if TSB ITB22-030 or ITB23-026 applies to your vehicle's VIN and software version. If the misfire occurs on cold starts or if P0300 is the only code, an ECM/TCM reprogram is a primary and highly likely fix.
3. Use a scan tool to view live data, specifically individual cylinder misfire counters (via Mode $06 or a manufacturer-specific function) and short/long-term fuel trims (STFT/LTFT). High positive fuel trims (>+10%) at idle point to a vacuum leak, while high trims under load suggest a fuel delivery problem.
4. If misfire counters point to a specific cylinder, focus diagnostics there. Swap the ignition coil with a known good cylinder and see if the misfire follows the coil.
5. If no specific cylinder is identified or if software is ruled out, inspect all spark plugs for wear, damage, or fouling. Replace as a set if they are worn or past their service life.
6. Inspect the intake system for vacuum leaks. A smoke test is the most effective way to find leaks that aren't visually apparent.
7. Check fuel pressure. For the VQ35DD, this involves checking both the low-pressure side (typically 35-65 PSI) and the high-pressure side (500-2,500+ PSI), which requires specialized equipment.
8. If the above steps do not resolve the issue, more advanced diagnostics are needed, such as testing fuel injectors (a 'Power Balance' test can help isolate a faulty one), checking for excessive carbon buildup on intake valves, and testing crank/cam sensors, especially if stalling occurs when hot.

Parts You'll Likely Need

• Engine Control Module (ECM) Reprogram — A known software issue on 2022-2023 models can cause a false P0300 code. This is a primary, vehicle-specific fix to investigate first per TSBs ITB22-030 and ITB23-026.
  Trusted brands: Infiniti Dealer Service
  OEM price range: $100-$250 (Labor)
  Aftermarket price range: N/A
• Spark Plugs (OEM #22401-EW61C) — Spark plugs are a common wear item and a leading cause of misfires. Fouled or worn plugs cannot create a strong enough spark for complete combustion.
  Trusted brands: NGK, Denso
  OEM price range: $100-$150 (Set of 6)
  Aftermarket price range: $60-$100 (Set of 6)
• Ignition Coil (OEM #22448-JA11C) — An intermittently failing ignition coil can cause random misfires before it fails completely and triggers a cylinder-specific code. Heat and age are common causes of failure.
  Trusted brands: Hitachi, Infiniti OE
  OEM price range: $70-$120 (per coil)
  Aftermarket price range: $40-$80 (per coil)

Related Codes That Often Appear With This One

• P0301-P0306 — These codes specify which cylinder is misfiring (P0301 for cylinder 1, etc.). They often appear with P0300 and help narrow down the search to a specific coil, plug, or injector.
• P0171/P0174 — System Too Lean (Bank 1 / Bank 2). These codes often accompany P0300 when the cause is a vacuum leak or a fuel delivery issue, as the unmetered air or lack of fuel affects all cylinders.

Technical Service Bulletins (TSBs) & Recalls

• ITB23-026: MIL IS ON WITH DTC P0300 STORED IN THE ECM (2022-2023 QX60)
• ITB22-030: MISFIRE DTCS STORED IN THE ECM DURING COLD START (2022 QX60)
• NTB22-069: MISFIRE DTCS STORED IN THE ECM DURING COLD START (2022 Nissan Pathfinder)

Platform-Specific Known Issues

• Infiniti Technical Service Bulletin ITB22-030 addresses an issue on the 2022 QX60 where P0300, P0301, P0302, P0303, P0304, P0305, or P0306 may be stored during a cold start warm-up cycle without any drivability concerns. The prescribed fix is to reprogram the ECM.

Mechanic-Grade Diagnostic Values

• Short-Term (STFT) and Long-Term (LTFT) Fuel Trims — expected: Within +/- 5% at idle and under load.. Failure: Consistently positive trims >+10% indicate a lean condition. If high only at idle, a vacuum leak is likely. If high only under load, a fuel delivery issue (pump, filter) is likely.
• Fuel Pressure (Low-Pressure Side) — expected: 35 - 65 PSI. Failure: Pressure that is below specification or drops significantly under load indicates a weak in-tank fuel pump or clogged filter.
• Fuel Pressure (High-Pressure Side) — expected: 500 - 2,500+ PSI. Failure: Readings outside the manufacturer's specified range for given RPMs indicate a problem with the high-pressure mechanical fuel pump. Requires specialized tools to measure.
• Idle Air Volume Learning Conditions — expected: Engine Coolant Temp: 70-100°C (158-212°F), Battery Voltage: >12.9V (at idle), Transmission warmed up.. Failure: These are not failure indicators, but required preconditions for performing the Idle Air Volume Learning service function with a scan tool, as specified in TSB ITB22-030.

Scan Tool Commands That Help

• Infiniti CONSULT or advanced professional scanner: Power Balance Test — This function is used to isolate a misfiring cylinder when only a general P0300 code is present. The tool deactivates one cylinder at a time, and the technician observes the drop in engine RPM. A cylinder that shows little or no RPM drop when deactivated is the one that is not contributing properly.
• Infiniti CONSULT or equivalent: Idle Air Volume Learning — This procedure must be performed after cleaning the throttle body or replacing the ECM. Failure to do so can result in an unstable or high idle, which could be mistaken for a misfire symptom. TSB ITB22-030 specifies this procedure as part of its diagnostic flow.

Real Owner Repair Stories

• Motor Vehicle Maintenance & Repair Stack Exchange (2014 Infiniti QX60) — P0300, hesitation on acceleration, and a specific hot-stall condition: after driving 30+ minutes, the car would stumble and stall after a brief park, refusing to restart until cooled down.
  ❌ Tried (didn't work) Spark plugs, Ignition coils
  ✅ What actually fixed it The user reported that replacing the crankshaft position sensor and one of the four camshaft position sensors resolved all the issues.
• YouTube channel 'G Auto Repair' (2020 Infiniti QX60) — P0302 (Cylinder 2 Misfire), strong smell of raw fuel, very wet and black spark plug. The Infiniti dealer had diagnosed engine sludge and quoted $27,000 for a new engine.
  ❌ Tried (didn't work) Dealer diagnosis of a sludged engine requiring replacement.
  ✅ What actually fixed it The actual cause was a single stuck-open fuel injector on cylinder 2. Replacing the faulty injector completely resolved the misfire.

OEM Part Supersession History

• 22448-JA10A, 22448-JA10C, 22448-JA12D → 22448-JA11C — Standard part revision and consolidation by the manufacturer.
• N/A → N/A — N/A
  Heads up: The fuel rail and injector assembly for the 2022-2024 INFINITI QX60 is NOT compatible with the 2022-2024 Nissan Pathfinder, despite sharing the VQ35DD engine and platform. The part numbers are different and they are not interchangeable.

Model Year Variations Within This Range

• 2022 vs 2023: While the engine and transmission hardware are identical, the software fix for P0300 differs slightly. TSB ITB23-026, which addresses P0300, directs technicians to reprogram the ECM on both 2022 and 2023 models, but specifies reprogramming the Transmission Control Module (TCM) on 2023 models as part of the procedure. This suggests a software logic change in the 2023 TCM related to misfire detection or reporting.