P0174System Too Lean (Bank 2)
The Bank 2 equivalent of P0171: fuel trim on Bank 2 is maxed out trying to compensate for a lean condition.
Definition
P0174 is the Bank 2 counterpart to P0171. When P0171 and P0174 appear together, the cause is almost always a shared component (MAF, intake gasket, large vacuum leak) rather than a bank-specific part.
Common causes
- Shared vacuum leak affecting both banks
- Failing MAF sensor
- Weak fuel pump
Common misdiagnoses
- Chasing bank-specific causes when both P0171 and P0174 are present together.
Troubleshooting steps
1.Confirm whether P0171 is also present
If both codes set together, focus on shared causes (MAF, large vacuum leak, fuel pump).
2.Follow the P0171 procedure
Apply the lean-condition diagnostic steps to the shared components first.