how to fix the check engine light on my Toyota RAV4 Fifth Generation (2019-present) with code P0171

Solution

1. Preparation

• Gather tools and parts needed: OBD-II scanner, fuel pressure gauge, multimeter, socket set, replacement parts (if needed).
• Ensure the vehicle is parked on a flat surface, and the engine is cool.

2. Inspect Air Intake System

• Tools Required: Visual inspection, flashlight.
• Check all hoses connected to the air intake for cracks, tears, or loose connections.
• Tighten or replace any damaged hoses as necessary.
• Inspect the air filter and replace it if dirty.

3. Test Fuel Pressure

• Tools Required: Fuel pressure gauge.
• Locate the fuel rail Schrader valve.
• Connect the fuel pressure gauge to the valve.
• Turn the ignition to the "ON" position without starting the engine and record the pressure reading.
• If the pressure is below specifications, check the fuel pump and filter for issues.

4. Clean or Replace MAF Sensor

• Tools Required: Socket set, cleaning spray for MAF sensors.
• Disconnect the MAF sensor connector.
• Remove the MAF sensor from the intake assembly.
• Clean the sensor gently with MAF sensor cleaner or replace it if damaged.

5. Inspect Vacuum Lines

• Tools Required: Visual inspection, flashlight.
• Check all vacuum lines connected to the intake manifold for signs of wear or damage.
• Replace any cracked or disconnected lines.

6. Check ECT Sensor

• Tools Required: Multimeter.
• Locate the ECT sensor.
• Disconnect the sensor and measure its resistance with a multimeter.
• Compare the readings to the manufacturer's specifications; replace if out of range.