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

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

Solution

1. Preparation

• Gather necessary tools and parts.
• Disconnect the negative battery terminal to prevent electrical shorts.

2. Inspect Air Intake System

• Tools Required: Screwdriver set, flashlight
• Visually inspect the air intake hoses and connections for cracks or leaks.
• Tighten any loose clamps and replace damaged hoses.

3. Check Fuel Pressure

• Tools Required: Fuel pressure gauge
• Locate the fuel pressure test port on the fuel rail.
• Connect the fuel pressure gauge and turn the ignition key to the "ON" position (do not start the engine).
• Check the pressure reading against the specifications in the service manual. If low, inspect the fuel pump and fuel filter.

4. Clean or Replace MAF Sensor

• Tools Required: MAF cleaner or appropriate solvent, screwdriver
• Locate the MAF sensor in the air intake path.
• Disconnect the electrical connector and unscrew the sensor from its mounting.
• Clean the sensor elements carefully with MAF cleaner. If damaged, replace the sensor.

5. Inspect and Clean Fuel Injectors

• Tools Required: Injector cleaner, fuel injector cleaning kit (if necessary)
• Remove the fuel rail to access the injectors.
• Inspect each injector for leaks or clogs. Use an injector cleaner to clean or replace any faulty injectors.

6. Address Vacuum Leaks

• Tools Required: Smoke machine or soapy water
• Use a smoke machine to introduce smoke into the intake system; observe for smoke escaping which indicates a leak.
• Alternatively, spray soapy water around suspected areas and look for bubbles indicating a vacuum leak.