What are the symptoms of a malfunctioning throttle position sensor in a 2020 Toyota Highlander?

Toyota Highlander Fourth Generation (2020-present)

Error Codes

2-3 hours

Time

medium

Difficulty

medium

Severity

Error Code: P0120, P0121, P0122, P0123

4 min read

744 words

Problem Statement

Learn about the symptoms, diagnostic steps, and repair instructions for a malfunctioning throttle position sensor (TPS) in a 2020 Toyota Highlander.

Error Code

P0120, P0121, P0122, P0123

Affected Component

Throttle Position Sensor (TPS)

Estimated Time

2-3 hours

Symptoms

•Check Engine Light
•Erratic Engine Behavior
•Poor Fuel Economy
•Delayed Response
•Unresponsive Accelerator
•Over-revving or Under-revving

Diagnostic Steps

1
Scan for Diagnostic Trouble Codes
2
Visual Inspection
3
Testing the TPS
4
Check the Signal to the ECU

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
•Digital multimeter
•Basic hand tools (screwdrivers, wrenches)
•Wiring diagram for TPS (optional)
•Safety glasses and gloves

Related Faults

Share this solution

Comments

No comments yet

Be the first to share your thoughts

Back to Generation

Symptoms of a Malfunctioning Throttle Position Sensor (TPS) in a 2020 Toyota Highlander

The throttle position sensor (TPS) is crucial for optimal engine performance, as it informs the engine control unit (ECU) of the throttle's position. A malfunctioning TPS can lead to various symptoms, affecting vehicle performance and drivability. Here are the primary symptoms to watch for:

Common Symptoms

Check Engine Light:
- The most prominent indicator of a TPS issue is the illumination of the check engine light on the dashboard. A diagnostic trouble code (DTC) related to the TPS may be stored in the vehicle's ECU.
Erratic Engine Behavior:
- Unstable engine idle, such as surging or stalling.
- Inconsistent acceleration, where the vehicle may hesitate or surge during acceleration.
Poor Fuel Economy:
- The engine may run too rich or too lean due to incorrect throttle position readings, leading to decreased fuel efficiency.
Delayed Response:
- A noticeable delay in acceleration when pressing the accelerator pedal.
Unresponsive Accelerator:
- The vehicle may not respond when the throttle pedal is pressed, indicating a potential failure in the TPS or related components.
Over-revving or Under-revving:
- The engine may rev higher than expected or fail to reach the desired RPMs, particularly during acceleration.

Tools Required

OBD-II scanner
Digital multimeter
Basic hand tools (screwdrivers, wrenches)
Wiring diagram for TPS (optional)
Safety glasses and gloves

Step 1: Scan for Diagnostic Trouble Codes

Connect the OBD-II scanner to the vehicle's diagnostic port.
Turn the ignition to the 'ON' position without starting the engine.
Retrieve any stored DTCs and pay special attention to codes related to the TPS (e.g., P0120, P0121, P0122, P0123).

Step 2: Visual Inspection

Inspect the TPS wiring and connectors for any signs of damage, corrosion, or loose connections.
Ensure the TPS is securely mounted to the throttle body.

Step 3: Testing the TPS

Disconnect the TPS connector.
Set the multimeter to the resistance (ohms) or voltage setting (depending on the type of TPS; most are potentiometer types).
Measure the resistance or voltage while manually moving the throttle plate from closed to fully open.
- For a potentiometer-type TPS, the resistance should change smoothly without any dead spots.
- For a voltage-type TPS, the voltage should vary linearly from 0.5V (closed) to about 4.5V (fully open).
Check for any fluctuation or drop in readings that might indicate a faulty sensor.

Step 4: Check the Signal to the ECU

Reconnect the TPS and use the multimeter to measure the voltage at the TPS signal wire while the engine is running.
Compare the readings to factory specifications. If the readings are outside of the acceptable range, the TPS is likely faulty.

Repair Instructions

Step 1: Removal of the Old TPS

Ensure the engine is off and the key is removed from the ignition.
Disconnect the negative battery terminal to prevent any electrical shorts.
Remove any engine covers or components obstructing access to the throttle body.
Unplug the TPS connector.
Remove the screws or bolts securing the TPS to the throttle body.
Gently pull the TPS off the throttle body.

Step 2: Installation of New TPS

Position the new TPS onto the throttle body, aligning it with the mounting holes.
Secure it with screws or bolts and tighten to the manufacturer’s specifications.
Reconnect the TPS electrical connector.
Reattach any components or covers that were removed.

Step 3: Calibration and Testing

Reconnect the negative battery terminal.
Start the engine and allow it to reach operating temperature.
Use the OBD-II scanner to clear any DTCs stored in the ECU.
Test drive the vehicle to confirm that the symptoms have been resolved and monitor for any reoccurring codes.

Step 4: Final Checks

After a successful test drive, re-scan the vehicle to ensure no DTCs have returned.
Verify that the throttle response is smooth and that the check engine light remains off.

Conclusion

A malfunctioning TPS in a 2020 Toyota Highlander can lead to various performance issues. By following the diagnostic steps and repair instructions outlined above, you can effectively address and resolve TPS-related problems. Always refer to the factory service manual for specific torque specifications and repair procedures.