my Toyota Camry Eighth Generation (2018-present) has a check engine light with code P0171

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical hazards.

2. Inspect and Repair Vacuum Leaks

• Sub-steps:
  1. Visually inspect all vacuum lines and intake hoses for cracks or disconnections.
  2. Use carburetor cleaner or a smoke machine to detect leaks; spray around suspected areas and listen for changes in engine RPM.
  3. Replace any damaged hoses or seals.

3. Clean the Mass Air Flow (MAF) Sensor

• Tools Required: MAF cleaner
• Sub-steps:
  1. Locate the MAF sensor in the air intake duct.
  2. Disconnect the electrical connector and remove the sensor from the housing.
  3. Spray the MAF cleaner onto the sensor element and allow it to dry completely before reinstallation.
  4. Reinstall the sensor and reconnect the electrical connector.

4. Check Fuel Pressure

• Tools Required: Fuel pressure gauge
• Sub-steps:
  1. Locate the fuel pressure test port on the fuel rail.
  2. Attach the fuel pressure gauge and turn the ignition to the ON position (without starting the engine).
  3. Compare the reading to the manufacturer's specifications (typically around 40-50 psi for most systems).
  4. If pressure is low, inspect the fuel pump and filter for issues.

5. Inspect and Test Oxygen Sensors

• Tools Required: Multimeter
• Sub-steps:
  1. Locate the upstream oxygen sensor in the exhaust system.
  2. Disconnect the sensor and check its resistance with a multimeter (refer to manufacturer specifications).
  3. If the sensor is faulty, replace it with a new one.