how to fix P0171 code on my Toyota RAV4 XA40 (2013-2018)

Solution

1. Preparation

• Tools Required: OBD-II scanner, vacuum gauge, MAF cleaner, fuel pressure gauge, socket set, screwdriver set, safety glasses, gloves.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect and Repair Vacuum Hoses

• Locate all vacuum hoses connected to the intake manifold.
• Inspect each hose for cracks, tears, or loose connections.
• Replace any damaged hoses with new ones, ensuring a tight fit.

3. Clean or Replace Mass Air Flow Sensor

• Disconnect the electrical connector from the MAF sensor.
• Remove the MAF sensor using a socket set and carefully detach it from the intake.
• Clean the sensor with MAF cleaner; allow it to dry completely before reinstallation.
• If damaged, replace the MAF sensor with an OEM part.

4. Check for Intake Manifold Leaks

• If vacuum leaks are suspected, perform a smoke test or use carburetor cleaner around the intake manifold sealing surfaces.
• If the idle changes when applying the cleaner, a leak is confirmed.
• Tighten or replace gaskets as necessary to ensure a proper seal.

5. Verify Fuel System Functionality

• Connect a fuel pressure gauge to the fuel rail.
• Start the engine and observe the fuel pressure; it should match the specification for your vehicle (typically around 50-60 PSI).
• If the pressure is low, inspect the fuel pump, filter, and fuel injectors for issues.

6. Reassemble and Test

• Reconnect all components and hoses removed during the repair.
• Reconnect the negative battery terminal.
• Start the engine and let it idle to ensure that the check engine light does not return.