What does P0174 mean?

Bank 2 gets too much air or too little fuel and the ECU cannot compensate completely.

Why do I see P0171 and P0174 together?

Both banks lean points to a shared cause such as the MAF sensor, fuel pressure or a large vacuum leak.

Fuel and air metering

P0174 — System Too Lean (Bank 2)

The ECU is adding more fuel than normal on bank 2 but the mixture still reads lean. Too much air or too little fuel is reaching the cylinders of the second bank.

Severity: Medium

Common causes

Vacuum or intake leak on the bank 2 side
Dirty or faulty MAF sensor
Weak fuel pump, clogged filter or low fuel pressure
Clogged or leaking injectors on bank 2
Exhaust leak before the bank 2 oxygen sensor

Symptoms

Rough idle or stalling
Hesitation and power loss
Misfire under load
Check engine light

How to check

Compare fuel trims of both banks: if both are lean, suspect MAF or fuel pressure; if only bank 2, suspect a local leak or injector
Inspect intake hoses and gaskets on bank 2 and smoke-test
Measure fuel pressure
Check the bank 2 oxygen sensor and exhaust for leaks

Can you keep driving?

Drivable for a short time, but a lean mixture raises temperatures and can damage the engine. Have it checked.

Frequently asked questions

What does P0174 mean?: Bank 2 gets too much air or too little fuel and the ECU cannot compensate completely.
Why do I see P0171 and P0174 together?: Both banks lean points to a shared cause such as the MAF sensor, fuel pressure or a large vacuum leak.

General reference information. It does not replace a diagnosis on your own vehicle. The same code can have different causes depending on make, model year and engine; check the manufacturer's documentation or ask a technician with a scan tool.