What Does P0171 Mean on a 2020 Nissan Maxima?
A P0171 code on your 2020 Nissan Maxima means the engine control module detected a lean air-fuel mixture on Bank 1. The 2020 Maxima is powered by a 3.5L V6 engine (VQ35DE) producing 300 horsepower. On this V6, Bank 1 is one of the two cylinder banks. A lean condition means the air-fuel ratio has drifted too far toward the air side on those cylinders.
The VQ35 engine family has been powering Nissan vehicles for over two decades. It's a proven, reliable engine, but lean conditions can develop with age and mileage.
Symptoms You Might Notice
- Check engine light on
- Rough idle
- Hesitation during acceleration
- Reduced fuel economy
- Engine surging at constant speed
- Possible misfires on Bank 1
Common Causes of P0171 on the 2020 Nissan Maxima
- Dirty MAF Sensor (30% likelihood) - The mass airflow sensor is a very common cause of P0171 on Nissan V6 engines. Contamination from dust and oil mist is typical.
- Vacuum Leak (25% likelihood) - Intake manifold gaskets, PCV hoses, and brake booster lines can develop leaks over time.
- Fuel Injector Carbon Buildup (25% likelihood) - The VQ35DE uses port injection, but injectors can still develop flow restrictions with age.
- Oxygen Sensor Degradation (20% likelihood) - A sluggish or biased upstream O2 sensor on Bank 1 can cause incorrect fuel calculations.
How to Diagnose the Problem
- Scan for all codes - Check for P0174, misfire codes, and O2 sensor codes.
- Monitor fuel trims - Compare Bank 1 and Bank 2 LTFT values. A big difference suggests a bank-specific issue.
- Clean the MAF first - This is the cheapest first step. Use dedicated MAF cleaner spray.
- Smoke test - Find vacuum leaks by pressurizing the intake system.
- Test fuel pressure and O2 sensors - Check for proper fuel delivery and sensor response times.
Repair Options and Cost Breakdown
- MAF sensor cleaning/replacement - $50 to $280. Most common and affordable fix.
- Vacuum leak repair - $150 to $450. Gasket replacement on the V6 requires moderate labor.
- Fuel injector cleaning or replacement - $200 to $500. Professional cleaning service is available.
- O2 sensor replacement - $150 to $400. The upstream Bank 1 sensor is the relevant one.
Can You DIY This Repair?
MAF sensor cleaning is easy. Vacuum hose checks are straightforward. O2 sensor replacement requires basic tools and ramps. Intake manifold and fuel injector work on the transverse V6 is more challenging due to space constraints.
Prevention Tips
- Clean the MAF sensor annually as preventive maintenance
- Replace the air filter every 15,000-20,000 miles
- Use Top Tier premium fuel as recommended for the Maxima
- Inspect vacuum hoses during oil changes
- Follow Nissan's maintenance schedule