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P0174: System running too lean (bank 2)

Bank 2 is getting too little fuel or too much air. Most often it is an air leak after the MAF sensor or low fuel pressure.

Code P0174 at a glance
CodeP0174
SystemEngine and transmission
GroupP01xx, Air and fuel metering
TypeGeneric: it means the same on every make
Can you keep driving?With care

What P0174 means

The ECU has added fuel to bank 2 up to its limit and the oxygen sensor still sees a lean mixture, meaning too much air. Bank 2 is the side of the engine opposite cylinder 1 and only exists on V or flat engines. If P0171 is also stored, the cause is usually something shared by both banks.

Most common causes

  • Cracked or loose vacuum hose, or a leaking intake gasket on bank 2
  • Dirty mass air flow (MAF) sensor reading less air than there really is
  • Blocked fuel filter or a weak fuel pump giving low pressure
  • Dirty or clogged injector on bank 2
  • Exhaust leak ahead of the bank 2 oxygen sensor
  • Faulty bank 2 oxygen sensor

Symptoms

  • Engine warning light on
  • Unstable idle or stalling
  • Lack of power or hesitation when accelerating
  • Hard starting from cold

Can you drive with P0174?

With care You can drive, but a lean mixture burns hotter, can cause misfires and over time may harm the engine or the catalytic converter. Get it checked soon.

How to check it

With the engine idling, note the long term fuel trim (LTFT) for bank 2, then check it again at around 2,500 rpm. If it drops a lot with revs, an air leak is likely; if it rises, suspect fuel delivery or the MAF sensor.

How to read and clear P0174 with Final OBD

Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0174 with this same explanation and whether it’s confirmed, pending or permanent.

With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.

Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.

Similar codes

P0174 is a generic code, so it means the same on any make, for example on Alfa Romeo, Audi, Dacia, Kia, Opel / Vauxhall, Toyota. See what Final OBD does on your car in makes and models.

What does code P0174 mean?

The ECU has added fuel to bank 2 up to its limit and the oxygen sensor still sees a lean mixture, meaning too much air. Bank 2 is the side of the engine opposite cylinder 1 and only exists on V or flat engines. If P0171 is also stored, the cause is usually something shared by both banks.

Can you drive with P0174?

You can drive, but a lean mixture burns hotter, can cause misfires and over time may harm the engine or the catalytic converter. Get it checked soon.

How do you clear P0174?

With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0174 comes back.