how to fix P0171 code on Toyota Corolla E140 (2006-2013)

Solution

1. Preparation

• Gather all necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Ensure the engine is cool before starting work.

2. Inspect and Repair Air Intake System

• Check all vacuum hoses for cracks or disconnections.
• Reconnect or replace any damaged hoses.
• Use a smoke test if necessary to identify hidden leaks.

3. Clean MAF Sensor

• Remove the MAF sensor from the air intake duct.
• Use MAF sensor cleaner to spray the sensing element carefully.
• Allow it to dry fully before reinstallation.

4. Test and Adjust Fuel Pressure

• Connect a fuel pressure gauge to the fuel rail.
• Start the engine and check if the fuel pressure meets the manufacturer's specifications (usually around 40-50 psi).
• If pressure is low, inspect the fuel pump and filter for issues.

5. Inspect and Clean Fuel Injectors

• Remove fuel injectors from the fuel rail.
• Use a fuel injector cleaner or ultrasonic cleaner to clean the injectors.
• Reinstall the cleaned injectors and ensure proper sealing.

6. Replace Faulty Oxygen Sensors (if applicable)

• If diagnostics indicate a malfunctioning oxygen sensor, remove the sensor from the exhaust system.
• Install a new sensor and ensure proper torque (usually around 30 ft-lbs).
• Reconnect the sensor's electrical connector.