How do I handle a malfunctioning engine coolant temperature sensor in my 2020 Toyota Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

2 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0117, P0118

4 min read

602 words

Problem Statement

Learn how to diagnose and repair a malfunctioning engine coolant temperature sensor in your 2020 Toyota Highlander with step-by-step instructions.

Error Code

P0117, P0118

Affected Component

Engine Coolant Temperature Sensor

Estimated Time

2 hours

Symptoms

•Check Engine Light
•Overheating
•Poor Fuel Economy
•Erratic Temperature Gauge
•Hard Starting

Diagnostic Steps

1
Visual Inspection
2
Scan for Codes
3
Voltage and Resistance Testing
4
Coolant Temperature 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
•Multimeter
•Infrared Thermometer or Thermocouple
•Socket set and ratchet
•Screwdrivers (flathead and Phillips)
•Torque wrench
•Safety glasses
•Gloves
•Replacement Engine Coolant Temperature Sensor (if necessary)

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Solution

Malfunctioning Engine Coolant Temperature Sensor in 2020 Toyota Highlander

Tools Required

OBD-II Scanner
Multimeter
Infrared Thermometer or Thermocouple
Socket set and ratchet
Screwdrivers (flathead and Phillips)
Torque wrench
Safety glasses
Gloves
Replacement Engine Coolant Temperature Sensor (if necessary)

Repair Instructions

Step 1: Safety Precautions

Ensure the engine is cool before starting any work.
Wear safety glasses and gloves for protection.

Step 2: Locate the Sensor

The Engine Coolant Temperature Sensor is typically located near the thermostat housing on the engine block.
Refer to your vehicle’s service manual for the exact location.

Step 3: Disconnect the Battery

Disconnect the negative terminal of the battery to prevent any electrical shorts.

Step 4: Remove the Old Sensor

Disconnect the Electrical Connector:
- Press the release tab and gently pull the connector off the sensor.
Remove the Sensor:
- Use the appropriate socket (usually 19mm or 21mm) to unscrew the old sensor from its mount.
- Be prepared for some coolant to spill, so have a drain pan ready.

Step 5: Install the New Sensor

Prepare the New Sensor:
- Apply a small amount of thread sealant (if recommended) to the threads of the new sensor.
Install the Sensor:
- Screw in the new sensor by hand to avoid cross-threading.
- Use a torque wrench to tighten the sensor to the manufacturer’s specified torque (usually around 15-20 ft-lbs).
Reconnect the Electrical Connector:
- Ensure it clicks into place securely.

Step 6: Reconnect the Battery

Reconnect the negative terminal of the battery.

Step 7: Test the Repair

Start the Engine:
- Allow the engine to reach operating temperature while monitoring the temperature gauge.
Check for Codes:
- Use the OBD-II scanner to clear any trouble codes and ensure none return after the engine has warmed up.
Verify Functionality:
- Monitor the operation of the engine coolant temperature sensor using the scanner or dashboard gauge to verify proper readings.

Conclusion

If the issue persists after replacing the coolant temperature sensor, further investigation into the engine’s cooling system, wiring harness, or engine control unit (ECU) may be required. It is advisable to consult a professional technician if the problem continues.