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P0174 — Fuel System Too Lean Bank 2
SeriousFuelPower derate likely — plan to stop soon
Seen on: Heavy Truck/Diesel
Fuel System Too Lean Bank 2. Common causes: Vacuum leak downstream.
Don't risk it — get a diesel tech on the truck.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Serious. Power derate likely — plan to stop soon.
Most likely causes
- Vacuum leak downstream
- Clogged injectors
- weak fuel pump
First moves (roadside)
- Smoke-test intake system
- check fuel pump output pressure
FAQ
What does P0174 mean?
Fuel System Too Lean Bank 2. Common causes: Vacuum leak downstream.
How serious is P0174?
Serious — Power derate likely — plan to stop soon.
What's the most likely cause of P0174?
The most common cause is: Vacuum leak downstream. Other possibilities include Clogged injectors; weak fuel pump.
Can I keep driving with P0174?
Power derate likely — plan to stop soon. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Throwing this code right now?
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.