What is P0175?
The P0175 code shows up when the Engine Control Module (ECM) or Powertrain Control Module (PCM) detects too much fuel or insufficient oxygen in the air fuel ratio.
Your car needs the correct air fuel ratio and spark (via spark plugs) for the perfect level of combustion to run your vehicle. And for a smooth ride, the fuel and oxygen levels need to change as you speed, slow down or rev up your engine.
How does this work?
The ECM or PCM sets the required air fuel ratio using the information sent by the mass airflow sensor (MAF sensor), crankshaft position sensor, and engine coolant temperature sensor according to your car’s engine speed.
The PCM then uses readings from the heated oxygen sensor (O2 sensor) to further adjust the air fuel ratio based on oxygen levels in the exhaust gas.
Ideally, your vehicle’s air fuel ratio should be 14:7:1, or 14:7 parts air and 1 part fuel.
But sometimes, the Engine Control Module or Powertrain Control Module may be unable to balance the air fuel ratio due to factors like a vacuum leak, faulty fuel injector, or fuel delivery issues.
If the imbalance causes a rich condition (excess fuel and insufficient oxygen,) the ECM registers a code P0175.