Why do I have both P0171 and P0174?

Both banks lean means a shared component is failing — usually the MAF sensor, fuel pump, or a large vacuum leak affecting both sides.

Can low fuel pressure cause P0174?

Yes — a weak fuel pump or clogged filter cannot deliver enough fuel to both banks, causing lean codes on both.

Medium Severity

Fuel System

Same as P0171 but on bank 2. If both P0171 and P0174 are present, the issue is likely shared (MAF, fuel pump, or large vacuum leak).

Common Fix

Fix vacuum leak or clean MAF

Estimated Cost (DIY)

$0 - $150

Vacuum leaklikely

Dirty MAF sensorlikely

Low fuel pressurepossible

Intake manifold gasket leakpossible

Need to read or clear this code?

Ready to fix it yourself?

Select your exact vehicle for a personalized guide

Why do I have both P0171 and P0174?: Both banks lean means a shared component is failing — usually the MAF sensor, fuel pump, or a large vacuum leak affecting both sides.
Can low fuel pressure cause P0174?: Yes — a weak fuel pump or clogged filter cannot deliver enough fuel to both banks, causing lean codes on both.

Need a diagnosis for your specific vehicle?

100% Free — No signup required