What does P0174 mean?
The computer constantly adjusts how much fuel it adds based on the oxygen sensors. This code means it has reached the limit of its correction on bank 2.
A lean code means the engine is getting more air than the fuel being delivered. Either air is getting in that the computer did not measure, or fuel delivery is falling short.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Check engine light
- Rough or unstable idle
- Hesitation when accelerating
- Lower fuel economy
- Sometimes misfire codes too
Common causes
- Vacuum leak (cracked hose, intake gasket, PCV valve or hose)
- Dirty or failing MAF sensor reading low
- Low fuel pressure (weak pump, clogged filter, bad regulator)
- Clogged or leaking fuel injectors
- Exhaust leak ahead of the upstream O2 sensor
How to diagnose P0174
- Look at long-term fuel trim. Readings above about +10% at idle point to a lean condition.
- If trims are high at idle and improve at 2,500 rpm, suspect a vacuum leak. If they get worse at higher rpm, suspect fuel delivery or the MAF.
- Smoke-test the intake for leaks.
- Check fuel pressure against spec.
- Clean the MAF sensor and recheck.
How to fix it
- Repair vacuum or intake leaks
- Clean or replace the MAF sensor
- Replace the PCV valve or hose
- Repair fuel pressure problems (pump, filter, regulator)
- Clean or replace injectors
Estimated repair cost
Likely repairs for P0174 run from about $20 to $1,300, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Vacuum leak repair (hose/gasket) | $100 - $450 |
| PCV valve / hose replacement | $50 - $300 |
| MAF sensor cleaning | $20 - $100 |
| Mass airflow sensor replacement | $150 - $450 |
| In-tank fuel pump (gasoline) | $500 - $1,300 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0174?
Moderate severity
You can usually drive it short term, but a lean engine can misfire and run hot, so fix it soon.
P0174 FAQ
P0171 and P0174 together, what does that mean?
When both banks are lean, the cause is almost always something both banks share: a vacuum leak, a dirty MAF sensor, a weak fuel pump or a clogged filter. A single-bank problem like one bad injector would not set both.
Can I drive with P0174?
Usually for a short time, but get it checked soon.
What does P0174 mean?
P0174 stands for "System Too Lean (Bank 2)". The computer constantly adjusts how much fuel it adds based on the oxygen sensors.
How much does it cost to fix P0174?
It depends on the cause. The likely repairs for P0174 range from about $20 to $1,300 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0174?
The most common causes are: vacuum leak (cracked hose, intake gasket, PCV valve or hose); dirty or failing MAF sensor reading low; low fuel pressure (weak pump, clogged filter, bad regulator).