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

Solution

1. Preparation

• Ensure the vehicle is parked on a level surface, and the engine is cool.
• Disconnect the battery to prevent any electrical shorts.
• Gather necessary tools: OBD-II scanner, multimeter, fuel pressure gauge, socket set, and cleaning materials.

2. Inspect Air Intake System

• Remove the engine cover if necessary.
• Visually inspect all vacuum hoses for cracks or disconnections; replace any damaged hoses.
• Check the intake manifold gasket for leaks; replace if necessary.

3. Clean or Replace MAF Sensor

• Disconnect the MAF sensor connector.
• Remove the MAF sensor from the intake duct.
• Use MAF cleaner to clean the sensor element; allow it to dry completely before reinstalling.
• If damaged, replace the MAF sensor with a new one.

4. Check Fuel Pressure

• Connect the fuel pressure gauge to the fuel rail test port.
• Turn the ignition key to the "ON" position (without starting the engine) to check fuel pressure; it should meet manufacturer specifications (typically around 43-50 psi).
• If the pressure is low, inspect the fuel pump and filter for any issues and replace as necessary.

5. Inspect Fuel Injectors

• Remove the fuel rail by detaching the clips and bolts securing it.
• Check the fuel injectors for clogs using a cleaning kit or replace them if they show signs of damage.
• Reinstall the fuel rail and connectors securely.

6. Verify Oxygen Sensor Operation

• Use a multimeter to check the voltage output of the upstream oxygen sensor while the engine is running.
• The sensor should fluctuate between 0.1 and 0.9 volts if functioning correctly; replace if the readings are constant or outside this range.