how to fix P0174 code in Toyota Corolla E170 (2013-2019)

Learn how to diagnose and fix P0174 system too lean issue in Toyota Corolla E170. Step-by-step guide with diagnostic procedures and repair instructions.

Solution

1. Preparation

• Gather tools and parts needed for the repair.
• Disconnect the negative battery terminal to prevent electrical shorts.
• Allow the engine to cool before starting work.

2. Inspect and Repair Vacuum Leaks

• Tools Required: Vacuum gauge, hose clamps, screwdriver
• Locate and inspect all vacuum hoses connected to the intake manifold.
• Use a vacuum gauge to check for leaks. If a leak is detected, replace the damaged hose or clamp.
• Reconnect all hoses securely.

3. Clean or Replace the MAF Sensor

• Tools Required: MAF sensor cleaner, torque wrench
• Locate the MAF sensor in the air intake duct.
• Disconnect the electrical connector and remove the sensor using a torque wrench.
• Spray the sensor with MAF cleaner and allow it to dry completely before reinstalling.
• Reinstall the sensor and reconnect the electrical connector.

4. Check and Clean the Throttle Body

• Tools Required: Throttle body cleaner, soft cloth, screwdriver
• Remove the air intake duct connected to the throttle body.
• Use throttle body cleaner and a soft cloth to clean any carbon buildup inside the throttle body.
• Reassemble the air intake duct securely.

5. Test the Fuel Pressure

• Tools Required: Fuel pressure gauge
• Connect the fuel pressure gauge to the fuel rail.
• Turn the ignition to the "ON" position (do not start the engine) and check the pressure reading against manufacturer specifications.
• If the pressure is low, inspect the fuel pump and filter for issues.

6. Inspect and Test Fuel Injectors

• Tools Required: Multimeter, injector cleaning kit
• Disconnect the fuel injector connectors and test the resistance with a multimeter. Ensure it meets the specifications.
• If faulty, replace the injector. Otherwise, use an injector cleaning kit to clean the injectors.