StopOrDrive

Enter a 5-character code such as P0420, P0301, or P0457.

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Codes starting with P are engine and transmission, B are body, C are chassis, and U are network communication. A 0 as the second character means a generic code shared by all makes; a 1 means a manufacturer-specific code, so its meaning depends on your brand.

A steady check engine light usually means get it checked soon. A flashing check engine light means an active misfire: reduce speed and stop driving as soon as it is safe.

That doesn't look like an OBD-II code

A valid code is one letter (P, B, C, or U) followed by four characters, for example P0420.

P0174 System too lean (Bank 2)

Can I drive with P0174?

Drive soon

OK to drive for now, but get it fixed within days to a couple of weeks, or the damage and the bill can grow.

The car usually runs, but it may hesitate, and running lean for a long time can cause misfires and overheat internal parts.

What does P0174 mean?

The engine is getting too much air or too little fuel on bank 2, and the computer has reached its limit trying to correct it. Bank 2 is the side of a V6 or V8 engine that does not have cylinder 1. P0171 is the same fault on bank 1.

What causes P0174?

A vacuum leak is the most common cause. If P0171 sets too, suspect a shared part such as the MAF sensor or fuel pump.

  1. Vacuum leak from a cracked hose or intake gasket
  2. Dirty or faulty mass airflow (MAF) sensor
  3. Weak fuel pump or clogged fuel filter
  4. Clogged fuel injectors
  5. Leaking PCV valve or hose

How much does it cost to fix P0174?

$50 – $1,000

Vacuum hose: $50–$200. MAF sensor: $150–$450. Fuel pump: $500–$1,000. Check hoses and the intake duct for cracks, and try cleaning the MAF sensor before buying parts. A shop smoke test finds small leaks you cannot hear or see.

What are the symptoms of P0174, and how can I confirm it?

Often none besides the light. Some cars hesitate, idle rough, or misfire, and a large vacuum leak can hiss. On a scan tool, bank 2 long-term fuel trim well above +10 percent confirms the lean condition. If only bank 2 is lean, check that side's intake gasket and injectors.

Will P0174 fail an emissions test, and should I clear it?

It fails any OBD-II based inspection while the light is on. After a repair, clear the code and drive normally for several days so the readiness monitors can finish. If P0174 returns, the leak or fuel problem is still there, and running lean longer can bring misfire codes.

Confirm the code yourself

A low-cost scanner lets you read the code, clear it, and see if it comes back before paying for a diagnosis.

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