What causes the engine light and traction control light to come on together in a 2020 Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

4 min read

640 words

Problem Statement

Learn how to diagnose and repair the Check Engine Light and Traction Control Light issues in a 2020 Toyota Highlander, including symptoms, diagnostic steps, and tools required.

Affected Component

Engine Control Unit, Wheel Speed Sensors, ABS Module, Transmission

Estimated Time

2-4 hours

Symptoms

•Both the Check Engine Light (CEL) and the Traction Control Light (TCL) illuminate on the dashboard.
•Reduced engine power.
•Sluggish acceleration.
•Erratic shifting.
•Unexpected behavior in traction control.

Diagnostic Steps

1
Connect OBD-II Scanner.
2
Read Diagnostic Trouble Codes (DTC).
3
Analyze Codes for engine and ABS/TCS issues.
4
Inspect Wheel Speed Sensors.
5
Check for other mechanical issues.

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
•Multimeter
•Basic hand tools (screwdrivers, socket set)
•Torque wrench
•Brake cleaner (if necessary)

Related Faults

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Solution

Engine Light and Traction Control Light Diagnosis for 2020 Toyota Highlander

Possible Causes

Faulty Wheel Speed Sensors: These sensors monitor the wheel rotation speed and can affect traction control.
Malfunctioning Engine Control Unit (ECU): The ECU controls engine performance and may register faults affecting both systems.
OBD-II Error Codes: Specific codes could indicate issues such as misfires, sensor failures, or other engine-related problems.
Transmission Issues: Problems in the transmission can trigger both lights.
ABS Module Issues: A malfunction in the Anti-lock Braking System (ABS), which is tied to traction control, can also cause the lights to illuminate.

Tools Required

OBD-II Scanner
Multimeter
Basic hand tools (screwdrivers, socket set)
Torque wrench
Brake cleaner (if necessary)

Step 1: Retrieve Diagnostic Trouble Codes (DTC)

Connect OBD-II Scanner:
- Locate the OBD-II port under the dashboard.
- Plug in the OBD-II scanner.
Read Codes:
- Turn the ignition to the "ON" position without starting the engine.
- Follow the scanner instructions to retrieve DTCs.
- Write down all codes for further analysis.

Step 2: Analyze Codes

Check for Engine Codes:
- Codes related to misfires (P0300-P0306), sensor issues (P0130-P0167), or other engine management faults need to be addressed first.
Check for ABS/TCS Codes:
- Look for codes like C1201, C1302, or other ABS-related codes indicating wheel speed sensor failures or communication issues.

Step 3: Inspect Wheel Speed Sensors

Locate Sensors:
- Identify the location of the wheel speed sensors on each wheel hub.
Visual Inspection:
- Inspect the wiring and connections for any signs of damage, corrosion, or disconnection.
Electrical Testing:
- Use a multimeter to check the resistance of each sensor (normally should be around 1 to 2 kΩ). If outside of this range, consider replacing the sensor.

Step 4: Check for Other Mechanical Issues

Inspect Brake Components:
- Check brake pads and rotors for excessive wear.
- Ensure there are no leaks in brake lines or the brake master cylinder.
Transmission Fluid Level:
- Check the transmission fluid level and condition. Low or dirty fluid can cause transmission issues.

Repair Instructions

Repairing Wheel Speed Sensors

Disconnect Battery:
- Disconnect the negative terminal to avoid any electrical shorts.
Remove and Replace Sensor:
- Remove the wheel and tire for access.
- Unbolt the sensor from the wheel hub.
- Install the new sensor and reconnect the wiring.
- Reassemble the wheel and tire, and reconnect the battery.

Addressing Engine Codes

Repair/Replace Faulty Components:
- For misfire codes, check spark plugs and ignition coils. Replace if necessary.
- For sensor-related codes, replace the faulty sensor (e.g., oxygen sensor) per the manufacturer’s specifications.
Clear Codes:
- Use the OBD-II scanner to clear codes after repairs.

Final Steps

Test Drive:
- Start the vehicle and take it for a test drive to ensure the lights do not reappear.
Recheck Codes:
- After the test drive, check the OBD-II scanner again to confirm that no new codes are present.
Monitor Performance:
- Ensure that the engine runs smoothly and traction control functions correctly.

Conclusion

Both the Check Engine Light and Traction Control Light illuminating simultaneously can indicate various underlying issues. Thorough diagnostics and repairs are crucial to resolving the problem effectively. If issues persist after performing these steps, further investigation by a professional technician may be required.