What Does P0174 Mean on Your 2018 Nissan Altima?
A P0174 trouble code on your 2018 Nissan Altima means the ECM detected a lean air-fuel mixture on Bank 2. The 2018 Altima offers a 2.5-liter four-cylinder producing 179 horsepower or a 3.5-liter V6 making 270 hp. On the V6 model, Bank 2 is a distinct cylinder bank, making P0174 a clear indicator of a bank-specific lean condition. On the four-cylinder, the code may be sensor-related since it is a single-bank engine.
With the 2018 Altima now several years old, wear-related causes become more likely. Rubber hoses deteriorate, sensors age, and fuel system components lose efficiency over time. Addressing this promptly prevents more expensive damage.
Common Symptoms You May Notice
- Check engine light on
- Rough idle
- Hesitation during acceleration
- Decreased fuel economy
- Engine stalling at idle
- Power loss under load
Most Likely Causes of P0174 on the 2018 Altima
- Vacuum Leak - Aged rubber hoses, cracked intake boot, or leaking intake manifold gasket. The 2018 Altima is at prime age for rubber component deterioration.
- Dirty MAF Sensor - Years of driving accumulate contamination on the MAF sensor, causing underreported airflow.
- Worn O2 Sensor - The upstream O2 sensor degrades with age and mileage, sending increasingly inaccurate readings to the ECM.
- Fuel Pump Wear - Higher-mileage 2018 Altimas may have fuel pumps that cannot maintain adequate pressure under all conditions.
How to Diagnose the Problem
- Read all codes - Confirm P0174 and check for P0171 or misfire codes.
- Check fuel trims - Monitor LTFT values. Above 10 percent positive confirms lean condition.
- Inspect vacuum hoses - Look for cracks, hardening, or loose connections in all rubber hoses.
- Clean MAF sensor - Use MAF-specific cleaner.
- Test fuel pressure - Verify pressure meets Nissan specifications.
Repair Options and Cost Breakdown
The 2018 Altima has affordable parts and is easy to work on.
- Vacuum hose replacement - $5 to $30.
- Intake manifold gasket - $40 to $100, plus $150 to $300 labor.
- MAF sensor cleaning - $8 to $15.
- MAF sensor replacement - $70 to $160, plus $40 to $80 labor.
- O2 sensor replacement - $60 to $180, plus $60 to $120 labor.
- Fuel pump replacement - $180 to $350, plus $120 to $250 labor.
Can You Fix This Yourself?
The 2018 Altima is very DIY-friendly. The engine bay is accessible, parts are cheap, and the Altima owner community has extensive repair guides. MAF cleaning, vacuum hose replacement, and sensor swaps are all straightforward. Fuel pump access through the rear seat area is manageable with basic tools and patience.
Prevention Tips
- Replace air filter every 15,000 miles
- Inspect vacuum hoses annually for cracking
- Use quality fuel to keep injectors clean
- Clean MAF sensor every 20,000 to 30,000 miles
- Consider replacing O2 sensors around 100,000 miles as preventive maintenance