What does P0174 mean?
System Too Lean (Bank 2)
Direct Answer
P0174 is identical to P0171 but applies to Bank 2 — the opposite bank from cylinder 1 on V6 and V8 engines. If both P0171 and P0174 appear together, a shared component (MAF sensor, fuel pump, fuel filter) is almost always the cause rather than a bank-specific issue.
Common Symptoms
- ✓Check engine light on
- ✓Rough idle
- ✓Hesitation under load
- ✓Poor fuel economy
- ✓Possible misfires on Bank 2 cylinders
Common Causes
- 01Vacuum leak on Bank 2 intake runners
- 02Dirty MAF sensor (if both P0171 and P0174 set)
- 03Weak fuel pump (affects both banks)
- 04Faulty Bank 2 upstream oxygen sensor
- 05Clogged Bank 2 fuel injectors
How to Fix P0174
Note if P0171 is also present
Both codes together = shared problem. Start with the MAF sensor and fuel pressure rather than bank-specific components.
Check Bank 2 vacuum lines
On V-type engines, Bank 2 vacuum hoses are often harder to access and more prone to cracking. Inspect carefully with a flashlight.
Follow P0171 diagnostic steps for shared components
Clean MAF, check fuel pressure, inspect injectors.
Frequently Asked Questions
Why do P0171 and P0174 appear together?
When both banks show lean, the fault is almost always in a shared system — the MAF sensor, fuel pump, or fuel filter — rather than bank-specific components like O2 sensors or injectors.
Estimated Repair Cost
$50–$800
Same range as P0171 — diagnosis determines whether it is a shared or bank-specific repair.
Safe to Drive?
Yes — with caution
Safe for short distances. Address promptly to avoid catalyst damage.
Get a Full Diagnosis
Scan your vehicle live and let GaugeAI explain every code in plain English — with repair costs and step-by-step fixes.
Try GaugeAI Free