What Does P0172 Mean on Your 2023 Nissan Murano?
A P0172 code on your 2023 Nissan Murano means the engine control module has determined that Bank 1 of your 3.5-liter VQ35DD V6 is running too rich. The ECM continuously monitors the air-fuel ratio using oxygen sensors, and when the mixture stays richer than the target 14.7:1 stoichiometric ratio beyond what fuel trim adjustments can correct, this code is triggered. Your 2023 Murano's direct-injection V6 produces 260 horsepower, and keeping the fuel mixture properly balanced is essential for performance and efficiency.
Symptoms You Might Notice
- Check engine light illuminated on the dashboard
- Reduced fuel economy compared to the EPA-rated 23 mpg combined
- Dark or black exhaust smoke under acceleration
- Rough idle or slight engine vibration
- Hesitation during acceleration
- Fuel smell near the exhaust or engine bay
Common Causes of P0172 on the 2023 Murano
Here are the most frequent causes, ranked by likelihood for this specific engine:
- Dirty or Failing Mass Airflow Sensor — The MAF sensor measures the volume and density of air entering the engine. Contamination from road dust or oil vapor causes inaccurate readings, leading the ECM to over-fuel the engine. This is the most common P0172 trigger on Nissan V6 engines.
- Worn or Leaking Fuel Injectors — The 2023 Murano's VQ35DD uses high-pressure direct injection. Over time, injectors can develop slight leaks or fail to close completely, allowing extra fuel into the cylinders.
- Degraded Upstream Oxygen Sensor — The Bank 1 Sensor 1 oxygen sensor provides critical feedback for fuel mixture control. A slow-responding sensor sends delayed or inaccurate data to the ECM.
- Faulty Fuel Pressure Regulator — If the fuel pressure regulator allows higher-than-normal fuel pressure, the injectors will deliver more fuel per injection pulse than the ECM intends.
How to Diagnose the Problem
- Scan for additional codes — Check if there are companion codes like P0175 (Bank 2 rich) which would point to a system-wide issue like fuel pressure or the MAF sensor.
- Review fuel trim data — Long-term fuel trim (LTFT) significantly below zero (more negative than -10%) on Bank 1 confirms the ECM is pulling fuel to compensate for a rich condition.
- Test the MAF sensor — Compare live MAF readings against specifications. At idle, expect around 7-14 g/s. Clean with dedicated MAF cleaner if contaminated.
- Check O2 sensor response — Monitor the Bank 1 upstream sensor for proper switching between lean and rich (0.1-0.9V). Slow or stuck readings indicate a failing sensor.
- Verify fuel pressure — Use the scan tool to monitor fuel rail pressure. The direct injection system should hold specified pressures during different operating conditions.
Repair Options and Estimated Costs
- MAF sensor cleaning — $10-$30 DIY with aerosol MAF cleaner
- MAF sensor replacement — $140-$310 parts and labor
- Oxygen sensor replacement — $200-$400 parts and labor
- Fuel injector replacement — $350-$800 depending on number of injectors
- Fuel pressure regulator repair — $160-$380 parts and labor
Start with the cheapest fix first — clean the MAF sensor. If the code returns, move to the next most likely cause. The 2023 Murano may still be under Nissan's 5-year/60,000-mile powertrain warranty, so check your coverage before paying out of pocket.
Prevention Tips
- Replace the air filter at recommended intervals to protect the MAF sensor
- Use quality Top Tier gasoline to minimize injector deposits
- Keep up with scheduled maintenance per the Nissan owner's manual
- Address engine warning lights promptly to prevent cascading damage
- Consider a fuel system cleaning service every 30,000 miles