how to fix the P0171 code in a Toyota RAV4 Fourth Generation (2013-2018)?

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to ensure safety during repairs.
• Tools Required: OBD-II scanner, fuel pressure gauge, multimeter, socket set, cleaning spray for MAF.

2. Inspect and Repair Air Intake System

• Step 1: Visually inspect all air intake hoses for cracks or loose connections.
• Step 2: Tighten any loose clamps and replace damaged hoses.
• Step 3: Use a smoke machine if available to check for vacuum leaks.
• Step 4: If leaks are found, replace the affected components.

3. Fuel System Check

• Step 1: Connect the fuel pressure gauge to the fuel rail test port.
• Step 2: Turn the ignition to the "ON" position (do not start) and check the fuel pressure. It should be within manufacturer specifications (typically 40-50 psi).
• Step 3: If pressure is low, inspect the fuel pump and filter for clogs or malfunction. Replace as necessary.

4. Clean MAF Sensor

• Step 1: Locate the MAF sensor, usually found between the air filter and throttle body.
• Step 2: Disconnect the electrical connector and remove the sensor from the housing.
• Step 3: Spray MAF cleaner on the sensor elements (do not touch them) and let it dry completely before reinstallation.

5. Inspect and Test Oxygen Sensors

• Step 1: Locate the upstream oxygen sensor (before the catalytic converter).
• Step 2: Use a multimeter to check the voltage output of the sensor while the engine is running; it should fluctuate between 0.1V and 0.9V.
• Step 3: If the readings are outside this range, replace the oxygen sensor.