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

Solution

1. Preparation

• Gather tools: OBD-II scanner, fuel pressure gauge, multimeter, socket set, and cleaning supplies.
• Ensure the vehicle is parked on a level surface and the engine is cool.

2. Inspect and Repair Air Intake System

• Sub-step 1: Visually inspect the air filter and replace it if it's dirty or clogged.
• Sub-step 2: Check all vacuum hoses connected to the intake manifold for cracks or disconnections. Replace any damaged hoses.
• Sub-step 3: Inspect the intake manifold gasket for leaks. Replace if necessary.

3. Clean or Replace MAF Sensor

• Sub-step 1: Disconnect the MAF sensor connector.
• Sub-step 2: Remove the MAF sensor from the air intake duct.
• Sub-step 3: Clean the MAF sensor with MAF cleaner spray. Allow it to dry before reinstalling.
• Sub-step 4: Reconnect the MAF sensor and ensure it is securely fastened.

4. Check and Repair Fuel System

• Sub-step 1: Attach the fuel pressure gauge to the fuel rail and turn the ignition to the "ON" position without starting the engine. Check if the fuel pressure is at the specified range (usually 40-50 psi for most Corollas).
• Sub-step 2: If pressure is low, inspect the fuel pump and replace if necessary.
• Sub-step 3: Inspect and clean the fuel injectors using a professional injector cleaning kit or replace them if they are clogged.

5. Test and Replace Oxygen Sensors (if necessary)

• Sub-step 1: Use a multimeter to check the voltage output of the upstream oxygen sensor. It should fluctuate between 0.1V and 0.9V.
• Sub-step 2: If the sensor is not functioning properly, replace it with a new one.