Why does my 2020 Highlander's engine make a knocking noise?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

4 min read

645 words

Problem Statement

Learn how to diagnose and repair knocking noises in your 2020 Toyota Highlander with our step-by-step guide.

Affected Component

engine

Estimated Time

2-4 hours

Symptoms

•Audible Noise
•Vibration
•Loss of Power
•Warning Lights

Diagnostic Steps

1
Initial Inspection
2
Check Engine Oil
3
Use an OBD-II Scanner
4
Fuel Quality Check

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
•Mechanic's Stethoscope
•Torque Wrench
•Oil Pressure Gauge
•Engine Oil Dipstick
•Flashlight
•Basic Hand Tools

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Solution

Possible Causes of Knocking Noise

Engine Detonation (Knock)
Worn Engine Components: Bearings, pistons, or rods.
Low Oil Level/Quality: Insufficient lubrication causing metal-to-metal contact.
Fuel Quality Issues: Low octane fuel leading to pre-ignition.
Loose or Damaged Engine Mounts: Causing abnormal vibrations and sounds.
Exhaust System Issues: Loose components or exhaust leaks.

Tools Required

OBD-II Scanner
Mechanic's Stethoscope
Torque Wrench
Oil Pressure Gauge
Engine Oil Dipstick
Flashlight
Basic Hand Tools (socket set, wrenches, screwdrivers)
Torque Specifications Reference

Step 1: Initial Inspection

Visual Inspection: Open the hood and visually inspect for any loose hoses, wires, or components.
Listen Carefully: Start the engine and listen for the knocking noise. Use a mechanic’s stethoscope to pinpoint the noise source (top end vs. bottom end of the engine).

Step 2: Check Engine Oil

Check Oil Level: Use the dipstick to check the oil level. Ensure the oil is at the correct level.
Inspect Oil Condition: Look for signs of contamination (metal shavings, water, sludge). If oil is dirty, consider an oil change.
Check Oil Pressure: Attach an oil pressure gauge to verify the oil pressure is within specifications while the engine is running.

Step 3: Use an OBD-II Scanner

Scan for Codes: Connect the OBD-II scanner to the vehicle’s diagnostic port and check for any trouble codes related to the engine.
Analyze Codes: Look for codes that might indicate misfires, knock sensor issues, or fuel-related problems.

Step 4: Fuel Quality Check

Check Fuel Octane: Ensure that the fuel used meets the manufacturer’s recommended octane rating (usually 87 or higher for most Toyota engines).
Inspect Fuel System: Look for any signs of fuel leaks or issues with the fuel injectors.

Repair Instructions

Repair Step 1: Address Engine Oil Issues

If Oil is Low: Top off with the correct oil type as specified in the owner's manual.
If Oil is Dirty: Change the engine oil and filter. Use a quality oil that meets the manufacturer’s specifications.

Repair Step 2: Replace Worn Engine Components (if applicable)

If Knock Detected in Bottom End: Drain the oil and remove the oil pan. Inspect the connecting rod bearings and main bearings for wear.
Replace Worn Components: If bearings are worn, replace them. Ensure to use the correct torque specifications when reassembling.

Repair Step 3: Address Fuel Quality Issues

Add Fuel Additives: If low octane fuel is suspected, consider adding a fuel additive to boost octane levels temporarily.
Fuel Injector Cleaning: If injectors are suspected to be clogged, perform a cleaning or replace them as necessary.

Repair Step 4: Inspect Engine Mounts

Check Engine Mounts: Visually inspect the mounts for cracks or separation.
Replace Mounts if Necessary: If mounts are damaged, replace them following proper torque specifications.

Repair Step 5: Exhaust System Check

Inspect Exhaust Components: Look for loose or damaged components.
Tighten or Replace: Secure any loose parts or replace damaged sections of the exhaust system.

Conclusion

After performing these checks and repairs, start the engine again to see if the knocking noise persists. If it does, further evaluation by a professional technician may be necessary, as internal engine issues could be more severe and require more extensive repairs. Regular maintenance and using the correct fuel and oil can help prevent such issues in the future.