P0174 code definition
System Too Lean (Bank 2)
What the P0174 code means
Code P0174 indicates that there is a lean condition detected by the Engine Control Module (ECM). A lean condition will be created if there is too much air, and not enough fuel, in the air fuel ratio (AFR). The ECM is designed with the capability of adjusting a lean condition back to normal, but only in small to mediocre amounts. If the air fuel ratio requires more compensation to return to normal than the ECU is capable of, code P0174 may set.
What causes the P0174 code?
- An air leak after the mass air flow (MAF) sensor, such as a torn intake boot, or bad intake manifold gaskets
- A dirty or faulty mass air flow sensor
- Faulty oxygen sensor
- Incorrect fuel pressure
- Leaking positive crankcase ventilation (PCV) valve
- Clogged exhaust gas recirculation (EGR) Port
- Leaking brake booster
What are the symptoms of the P0174 code?
- Increased fuel consumption
- Check Engine Light will come on
- Rough or high idle
- Decreased acceleration
- Engine stalling
How does a mechanic diagnose the P0174 code?
- Performs a fuel pressure test
- Checks the intake system and vacuum lines for leaks
- Inspects the valve cover for worn hoses or leaks
- Inspects the PCV valve
- Tests the mass air flow sensor with a scan tool or multimeter
- Tests the related oxygen sensor with a scan tool or multimeter
Common mistakes when diagnosing the P0174 code?
- Replacing a component without first deeming it bad through testing
- Failing to check the intake system for tears or leaks
How serious is the P0174 code?
Generally, a lean condition is not that serious. However, be aware that there is a possibility of the lean condition being caused by a leak in the intake system. Leaks in the air intake may allow particles to enter the engine, which may be damaging.
What repairs can fix the P0174 code?
- Replacing mass air flow sensor
- Cleaning mass air flow Sensor
- Replacing faulty oxygen sensor
- Replacing PCV valve
- Replacing vacuum line
- Replacing EGR valve
- Replacing brake booster
- Replacing valve cover gasket
Additional comments for consideration regarding the P0174 code
Be sure to check the intake manifold and vacuum lines for leaks.
Need help with a P0174 code?
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