Locate the oxygen sensors: The oxygen sensors are located in the exhaust system, typically near the catalytic converter.
Check the oxygen sensor wires: Inspect the wiring harness for the oxygen sensors. Look for any loose connections, damaged wires, or corrosion. If you find any issues, repair or replace the wiring as required.
Clean the oxygen sensors: If the oxygen sensors are dirty or contaminated, they may not function correctly. Clean the oxygen sensors using a suitable cleaner and a soft cloth. Be careful not to damage the sensors.
Test the oxygen sensors: Use a multimeter to test the oxygen sensors. Disconnect the oxygen sensors from the wiring harness and connect the multimeter to the sensor terminals. Follow the manufacturer's instructions for the specific oxygen sensor to determine the correct testing procedure.
Inspect the vacuum lines: Check for any vacuum leaks in the engine bay. Vacuum leaks can cause the engine to run lean and can lead to the P0171 and P0174 codes.
Check the fuel pressure: Ensure the fuel pressure is within the recommended range for your vehicle. A low fuel pressure can lead to a lean fuel mixture and cause the P0171 and P0174 codes.
Inspect the fuel injectors: Clogged or faulty fuel injectors can also cause a lean fuel mixture and can lead to the P0171 and P0174 codes. Clean or replace the fuel injectors as needed.
Perform a mass air flow (MAF) sensor test: A faulty MAF sensor can also lead to a lean fuel mixture and cause the P0171 and P0174 codes. Clean the MAF sensor or replace it if necessary.
Reset the codes: Once the repairs are complete, clear the P0171 and P0174 codes from your vehicle's ECU. You can do this by using a code reader or by disconnecting the vehicle's battery for a few minutes.
Remember to consult your vehicle's service manual or seek assistance from a qualified mechanic if you are unsure how to perform any of these tasks.
