how to fix P0171 code in Toyota Corolla E210 (2019-2024)

Solution

1. Preparation

• Tools Required: OBD-II scanner, socket set, torque wrench, multimeter, vacuum gauge, MAF cleaner.
• Ensure the vehicle is parked on a level surface and the engine is cool.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect Air Intake System

• Visually inspect all intake hoses and connections for cracks or disconnections.
• Use a vacuum gauge to check for any vacuum leaks in the system.
• If any leaks are found, replace the damaged hoses or gaskets as necessary.

3. Clean or Replace MAF Sensor

• Locate the MAF sensor in the air intake duct.
• Disconnect the electrical connector and remove the MAF sensor from the duct.
• Clean the MAF sensor with MAF cleaner or replace it if it is damaged.
• Reinstall the MAF sensor and reconnect the electrical connector.

4. Check Fuel Delivery System

• Use a fuel pressure gauge to check the fuel pump pressure; it should meet manufacturer specifications (typically around 43-50 psi).
• If the pressure is low, inspect the fuel filter and replace it if clogged.
• Ensure the fuel pump is functioning properly; replace it if necessary.

5. Inspect Oxygen Sensors

• Check the upstream oxygen sensor with a multimeter to ensure it’s operating within the specified voltage range (typically 0.1V to 0.9V).
• If the sensor is not responding correctly, replace it with a new one.

6. Verify Engine Coolant Temperature Sensor

• Use a multimeter to check the resistance of the ECT sensor.
• Compare readings to the specifications in the service manual; replace the sensor if readings are out of range.