P0174: System Too Lean (Bank 2)
Bank 2 of a V engine is running lean and the computer cannot add enough fuel to fix it.
Severity: 2 of 4
Usually drivable for a short time with a steady light and normal running. Address it soon. Park it if misfire codes appear or the light flashes.
Estimate range covers the repairs listed below; see the cost breakdown. A flashing check engine light, a hot temperature gauge, or brakes that feel different mean stop driving and get help.
What P0174 means
P0174 is the bank 2 twin of P0171. The front oxygen sensor on bank 2 keeps reporting too much oxygen, and the fuel trims have reached their limit.
When P0174 appears alone, look for something on that side of the engine such as an intake gasket leak. When it appears with P0171, the cause is usually shared by both banks.
Common causes (cheapest likely first)
- Vacuum leak. The leading cause. Check PCV and brake booster hoses and intake boots.
- Dirty MAF sensor. Affects both banks and often sets P0171 and P0174 together.
- Intake manifold gasket leak on bank 2. A side specific leak.
- Low fuel pressure. Weak pump or restricted filter.
- Exhaust leak ahead of the bank 2 oxygen sensor. Lets air into the sensor reading.
Symptoms
- Steady check engine light
- Rough idle
- Hesitation
- Possible misfires on bank 2
DIY difficulty: Easy to moderate
Same approach as P0171. Start with hoses and the MAF sensor.
Tools: OBD-II scanner with fuel trim data, MAF sensor cleaner, Smoke tester (optional), Fuel pressure gauge
Estimated repair cost
This is an estimate, built from typical parts price ranges plus labor hours times an assumed shop rate of $110 to $190 per hour. Actual prices vary by vehicle, region, and shop. Diagnosis fees are often extra.
| Repair | Parts | Labor | Estimate (low / high) |
|---|---|---|---|
| Vacuum hose | $10 to $80 | 0.3 to 1.0 h | $10 + 0.3 × $110 = $43 $80 + 1.0 × $190 = $270 |
| MAF sensor cleaning or replacement | $10 to $250 | 0.2 to 0.5 h | $10 + 0.2 × $110 = $32 $250 + 0.5 × $190 = $345 |
| Intake manifold gasket | $20 to $150 | 1.5 to 4.5 h | $20 + 1.5 × $110 = $185 $150 + 4.5 × $190 = $1,005 |
Watch a repair video
System Too Lean: Code P0171 or P0174 (1A Auto). Third-party video, loads from YouTube (privacy-enhanced mode) only when you press play. Procedures vary by vehicle. Search YouTube for “P0174 fix” videos.
P0174 by make
Brand specific notes: Ford, Chevrolet. Other makes: the code works the same way; see all makes.
Repair manuals
Step-by-step service manuals with torque specs and wiring diagrams:
Haynes manuals Chilton manuals
Affiliate disclosure: links in this box may earn FixOrPark a commission at no extra cost to you.
Related codes
Check for recalls
Before paying for a repair, enter your VIN in the NHTSA recall lookup. Emissions parts may also be covered by a federal emissions warranty; check your warranty booklet.
FAQ
Is P0174 serious?
Not an emergency in most cases, but it can lead to misfires. Fix it within days or weeks, not months.
Can a brake booster hose cause P0174?
Yes. A leaking booster hose is a vacuum leak. A hard brake pedal can be a clue, and any brake feel change means stop driving and have it checked.