What P0174 Means for Your 2020 Nissan Frontier
Your 2020 Nissan Frontier has thrown a P0174 code, indicating that Bank 2 of the engine is running too lean. The 2020 Frontier comes with a 3.8-liter V6 engine (VQ38DD) producing 310 horsepower -- a significant upgrade from the previous 4.0L V6. This engine has a true V6 configuration with Bank 2 being the rear cylinder bank closest to the firewall.
A lean condition on Bank 2 means the ECM is detecting too much air or too little fuel in the combustion mixture on that side. The engine computer has been adding extra fuel to compensate, but the correction has exceeded its programmed limit, triggering the code.
Symptoms You Might Notice
- Check engine light illuminated
- Rough idle, especially noticeable in a truck at stop lights
- Loss of power during acceleration or when hauling cargo
- Decreased fuel economy (already a concern with a V6 truck)
- Hesitation when pressing the throttle
- Possible sputtering or misfiring at low RPM
Common Causes for the 2020 Frontier
- Vacuum Leak on Bank 2 (35% likelihood) -- The Frontier's engine bay gets exposed to dust and debris from off-road and work use, which accelerates rubber hose deterioration. Rear bank vacuum leaks are the top cause.
- Dirty MAF Sensor (30% likelihood) -- Trucks used on dusty roads or job sites see faster MAF sensor contamination. A dirty sensor underreports airflow to the ECM.
- Fuel Injector Issue on Bank 2 (20% likelihood) -- Clogged or partially blocked injectors on the rear bank reduce fuel delivery to those cylinders.
- Fuel Pump Weakness (15% likelihood) -- The fuel pump may struggle to maintain adequate pressure, especially under load when the truck is working hard.
Diagnosis Process
- Scan all codes -- Check for P0171 (Bank 1 lean) and misfire codes. Both banks lean means a common cause.
- Read fuel trims -- Bank 2 long-term fuel trim above +15% confirms the lean condition on that side.
- Smoke test the intake -- The most effective leak detection method. Focus on the rear bank intake connections and gaskets.
- Test the MAF sensor -- Compare readings to VQ38DD specifications at idle and under load.
- Check fuel pressure -- Test fuel rail pressure at idle and under load. Low pressure points to a pump or filter issue.
Repair Options
- Vacuum leak repair -- Replace cracked or brittle hoses and gaskets on the Bank 2 side of the intake.
- MAF sensor cleaning/replacement -- Start with MAF cleaner spray. Replace if still reading incorrectly.
- Fuel injector service -- Professional cleaning or replacement of restricted Bank 2 injectors.
- Fuel pump replacement -- Replace the in-tank fuel pump if pressure is below spec.
Estimated Repair Costs for the 2020 Frontier
- Vacuum leak repair: $120 - $450
- MAF sensor replacement: $160 - $380
- Fuel injector service/replacement: $250 - $650
- Fuel pump replacement: $500 - $900
Truck repairs can run slightly higher due to larger components and more difficult access in some areas.
Prevention Tips
- Replace the air filter more frequently if driving on dusty roads or job sites
- Use top-tier gasoline to reduce injector deposit buildup
- Inspect vacuum hoses during every oil change
- Keep the engine bay clean to reduce contamination risk
- Follow Nissan's maintenance schedule for the Frontier