P0174: System Too Lean (Bank 2)
Same as P0171 but on bank 2 of a V6 or V8. If both P0171 and P0174 are set, the problem affects the whole engine, like a big vacuum leak, MAF sensor or fuel pressure.
Green, yellow, red: three ways P0174 can look
The same code can be a quick fix or a reason to pull over. Match your situation to the closest example.
Keep an eye on it
Light on, drives normally.
Schedule a repair
Rough idle or the code returns. Schedule diagnosis soon.
Stop and get help
Lean codes with misfires or flashing light. Stop driving soon.
Symptoms you might notice
- Usually none at first
- Rough idle
- Hesitation
Common causes, cheapest first
- Vacuum leak
- Dirty MAF sensor
- Low fuel pressure
- Intake manifold gasket leak
- Clogged injectors on bank 2
What you can check before calling
- Check if P0171 is also set
- Listen for vacuum leaks
A code points to a system, not a part. Replacing parts based on the code alone is how people spend money without fixing the problem. Testing confirms the cause first.
Want the full story? Read our guide: P0171 "system too lean": causes and how to find the real one.
Generic codes (second character 0) mean the same thing on every vehicle. Some manufacturers add their own details, so check service information for your exact vehicle.
More fuel & air mixture codes
Look up another code
Cummins fault code (like 1922), J1939 SPN and FMI (like SPN 3251 FMI 0), or an OBD-II code (like P0420).
Questions
What does P0174 mean?
P0174 means "System Too Lean (Bank 2)". Same as P0171 but on bank 2 of a V6 or V8. If both P0171 and P0174 are set, the problem affects the whole engine, like a big vacuum leak, MAF sensor or fuel pressure.
Can I drive with code P0174?
It depends on what the vehicle is doing. Green: Light on, drives normally. Yellow: Rough idle or the code returns. Schedule diagnosis soon. Red: Lean codes with misfires or flashing light. Stop driving soon.
What causes P0174?
The most common causes are: vacuum leak; dirty MAF sensor; low fuel pressure.
Is P0174 a serious code?
It can be. Lean codes with misfires or flashing light. Stop driving soon.
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