What are the symptoms of a failing fuel injector in a 2020 Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

5 min read

887 words

Problem Statement

Learn how to diagnose and repair failing fuel injectors in a 2020 Toyota Highlander with detailed symptoms, diagnostic steps, and repair instructions.

Affected Component

fuel injector

Estimated Time

2-4 hours

Symptoms

•Hesitation during acceleration
•Rough idling
•Noticeable drop in engine power
•Sudden drop in miles per gallon (MPG)
•Frequent refueling
•Check Engine Light (CEL) illuminates
•Engine misfires
•Noticeable smell of gasoline
•Higher than normal output of exhaust emissions

Diagnostic Steps

1
Visual Inspection for fuel leaks
2
Use OBD-II scanner to read diagnostic trouble codes (DTCs)
3
Perform Fuel Pressure Test
4
Conduct Injector Balance Test
5
Perform Injector Cleaning if necessary

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Fuel pressure gauge
•Safety goggles
•Rags for cleanup
•Multimeter
•Noid light (optional)
•Fuel injector cleaning kit
•Socket set
•Torque wrench
•Screwdrivers
•New fuel injectors
•Fuel injector O-rings
•Shop towels

Related Faults

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Solution

1. Engine Performance Issues

Symptoms: Hesitation during acceleration, rough idling, or a noticeable drop in engine power.
Explanation: A malfunctioning injector may not supply the correct amount of fuel, leading to poor combustion.

2. Decreased Fuel Efficiency

Symptoms: A sudden drop in miles per gallon (MPG) and more frequent refueling.
Explanation: If the injector is leaking or stuck open, it can cause excessive fuel consumption.

3. Check Engine Light

Symptoms: The Check Engine Light (CEL) illuminates on the dashboard.
Explanation: The vehicle's onboard diagnostic system detects irregularities in the fuel system performance, often triggering a fault code related to the fuel injectors.

4. Misfires

Symptoms: Engine misfires, which can manifest as a rough engine running condition, poor acceleration, or vibrations.
Explanation: An injector that is clogged or failing to open can lead to incomplete combustion, causing misfires.

5. Fuel Odor

Symptoms: A noticeable smell of gasoline around the vehicle.
Explanation: A leaking injector can lead to fuel dripping onto the engine or onto the ground.

6. Increased Emissions

Symptoms: A higher than normal output of exhaust emissions.
Explanation: Incomplete combustion due to improper fuel delivery can increase harmful emissions.

Step 1: Preliminary Checks

Visual Inspection: Check for any visible signs of fuel leaks around the injector area.
Check Engine Light: Use an OBD-II scanner to read any diagnostic trouble codes (DTCs). Pay attention to codes related to fuel delivery or misfires.

Step 2: Fuel Pressure Test

Tools Required:
- Fuel pressure gauge
- Safety goggles
- Rags for cleanup
Instructions:
1. Locate the fuel rail on the engine.
2. Connect the fuel pressure gauge to the test port on the fuel rail.
3. Turn the ignition to the "ON" position without starting the engine to build pressure.
4. Read the pressure on the gauge; refer to the service manual for the correct specifications.
5. If the pressure is lower than specified, it may indicate a problem with the fuel pump or injectors.

Step 3: Injector Balance Test

Tools Required:
- Multimeter
- Noid light (optional)
Instructions:
1. Disconnect the electrical connector from each injector.
2. Use a multimeter to measure the resistance of each injector; compare the readings to the manufacturer’s specifications.
3. Optionally, use a noid light to check for pulse signal to each injector while cranking the engine.
4. If the signal is inconsistent, the injector may be failing.

Step 4: Injector Cleaning

Tools Required:
- Fuel injector cleaning kit (if necessary)
Instructions:
1. If injectors are suspected to be clogged, perform a cleaning procedure using a fuel injector cleaning kit.
2. Follow the manufacturer’s instructions to connect the cleaner to the fuel rail.
3. Run the cleaning solution through the injectors as directed.

Repair Instructions

If diagnostics confirm a failing fuel injector, follow these instructions to replace it:

Step 1: Preparation

Tools Required:
- Socket set
- Torque wrench
- Screwdrivers
- New fuel injectors
- Fuel injector O-rings (if not included with injectors)
- Shop towels

Step 2: Remove the Engine Cover

Use a socket to remove any bolts securing the engine cover.
Carefully lift the cover off and set it aside.

Step 3: Relieve Fuel Pressure

Locate the fuel pump fuse in the fuse box.
Start the engine and pull the fuel pump fuse while the engine runs until it stalls.
Turn off the ignition and disconnect the negative battery terminal.

Step 4: Remove the Fuel Rail

Disconnect the electrical connectors from the fuel injectors.
Loosen the fuel rail mounting bolts using a socket.
Carefully lift the fuel rail off the intake manifold, ensuring not to damage the injectors.

Step 5: Replace Injectors

Remove the old injectors from the rail by gently twisting and pulling them out.
Apply a small amount of engine oil to the O-rings of the new injectors.
Install the new injectors into the fuel rail until they click into place.

Step 6: Reassemble

Reinstall the fuel rail onto the intake manifold, ensuring proper alignment.
Tighten the fuel rail bolts to the manufacturer’s specifications using a torque wrench.
Reconnect the electrical connectors to each injector.
Reinstall the engine cover.

Step 7: Reconnect Battery and Test

Reconnect the negative battery terminal.
Turn the ignition to the ON position (do not start) to prime the fuel system.
Check for leaks around the injectors and fuel rail.
Start the engine and monitor its performance.

Step 8: Reset Check Engine Light

If applicable, use the OBD-II scanner to clear any stored trouble codes.

By following these detailed steps, you can diagnose and repair issues related to failing fuel injectors in a 2020 Toyota Highlander. Always refer to the manufacturer's service manual for specific torque settings and procedures.