CarSenseTrouble codes › P0174

P0174: System Too Lean (Bank 2)

What this check-engine code means in plain English, what usually causes it, and what a fix typically costs.

Severity: Monitor — not an emergency, but don't ignore it

What P0174 means

The engine control module has detected that the air-fuel mixture on Bank 2 (the side of the engine opposite cylinder #1) is too lean, meaning there's too much air or not enough fuel. The computer tries to compensate by adding more fuel, but the mixture remains outside normal parameters.

What causes P0174?

Likely
Vacuum leakCracked hoses, intake gaskets, or PCV system leaks allow unmetered air into the engine.
Likely
Dirty or failing mass airflow (MAF) sensorA contaminated or faulty MAF sensor provides incorrect airflow readings to the computer.
Possible
Weak fuel pump or clogged fuel filterInsufficient fuel pressure prevents the engine from getting enough fuel to match the incoming air.
Possible
Faulty oxygen sensorA failing O2 sensor on Bank 2 may send incorrect lean readings to the computer.

Is P0174 safe to drive?

Drive it?
Usually yes, short-term
Watch for
Rough idle, hesitation, or poor fuel economy
DIY-friendly?
Checking for vacuum leaks and cleaning the MAF sensor are DIY-friendly; fuel system work requires more skill.

You can typically drive short distances with this code, but prolonged lean conditions can damage the catalytic converter and reduce engine performance. Address it within a few days to avoid more expensive repairs.

P0174 repair cost

~$100 – $800+

Industry-average estimates. Cost depends on the root cause—a vacuum hose may cost under $100, while fuel pump replacement or intake gasket work can exceed $600.

Which one is it for your car?

Plug a cheap OBD2 adapter into your car and CarSense reads your codes and tells you the likely cause and a real cost for your exact vehicle — free to scan, no proprietary dongle.

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