FAULTBASE
Error CodesASKCars
© 2025 FAULTBASE
All rights reserved.
v2.0.0 • Production
ContactPrivacyImpressum
Home/Cars/Toyota/Highlander/Third Generation (2014-2019)/what does B1491 code mean for Toyota Highlander Third Generation (2014-2019)

what does B1491 code mean for Toyota Highlander Third Generation (2014-2019)

Toyota Highlander Third Generation (2014-2019)

Error Codes
Severity: mediumDifficulty: mediumError Code: B14912-4 hours
3 min read
473 words

Problem Statement

Learn how to diagnose and fix B1491 HVAC issues in Toyota Highlander (2014-2019). Step-by-step guide with diagnostic procedures and repair instructions.

Error Code
B1491
Component
HVAC
Repair Time
2-4 hours

Safety Warnings

  • ⚠Disconnect battery before working on electrical systems.
  • ⚠Allow the vehicle to cool down before inspecting the A/C system to prevent burns.

Symptoms

  • •Air conditioning not functioning properly
  • •Inconsistent cabin temperature
  • •A/C system blowing warm air
  • •Warning light illuminated on the dashboard
  • •Possible issues with climate control settings

Diagnostic Steps

  1. 1Scan for error codes using an OBD-II scanner to confirm B1491 and check for any additional related codes.
  2. 2Inspect the ambient temperature sensor for any physical damage or disconnection.
  3. 3Check the A/C amplifier for proper electrical connections and signs of corrosion.
  4. 4Test the ambient temperature sensor's resistance with a multimeter to ensure it falls within the manufacturer's specifications.
  5. 5Verify the integrity of the wiring harness connecting the sensor and amplifier; look for frayed or damaged wires.
  6. 6Clear the trouble codes and perform a test drive to see if the code reappears.

Solution

Solution

1. Preparation

  • Gather tools and parts required for the repair.
  • Disconnect the vehicle battery to avoid electrical shorts.

2. Inspect and Replace Ambient Temperature Sensor

  1. Locate the ambient temperature sensor, typically found near the front grille.
  2. Disconnect the electrical connector from the sensor.
  3. Remove the sensor from its mounting bracket (if applicable).
  4. Install the new ambient temperature sensor by reversing the removal steps.
  5. Reconnect the electrical connector ensuring it is secure.

3. Check and Repair A/C Amplifier Connections

  1. Locate the A/C amplifier, usually found under the dashboard or in the engine compartment.
  2. Inspect all connectors for corrosion or damage; clean or replace as necessary.
  3. Ensure the amplifier is securely mounted and connections are tight.
  4. If the A/C amplifier is faulty, remove and replace it with a new unit.

4. Reconnect Battery and Test

  1. Reconnect the vehicle battery.
  2. Start the vehicle and turn on the A/C system.
  3. Verify that the air conditioning is functioning correctly and monitor for the return of the B1491 code.

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
  • Socket set
  • Screwdrivers
  • Pliers

Parts Required

  • Ambient temperature sensor
  • A/C amplifier (if needed)

Additional Information

Error CodeB1491
Component

HVAC

Repair Time

2-4 hours

Difficulty

medium

Severity

medium

Tools

5 items

Parts

2 items

Related Faults

  1. how to resolve P0302 engine misfire code in Toyota Highlander Third Generation (2014-2019)

    Learn how to diagnose and fix P0302 engine misfire in Toyota Highlander (2014-2019). Step-by-step guide with diagnostic procedures and repair instructions.

    P0302Engine5 symptoms

  2. why is my Toyota Highlander shaking when I accelerate

    Learn how to diagnose and fix shaking during acceleration in Toyota Highlander. Step-by-step guide with diagnostic procedures and repair instructions.

    Suspension5 symptoms

  3. why does my Toyota Highlander make a loud clunk when shifting gears

    Learn how to diagnose and fix loud clunking noise during gear shifts in Toyota Highlander. Step-by-step guide with diagnostic procedures and repair instructions.

    Transmission5 symptoms

  4. how to troubleshoot the power windows on Toyota Highlander Third Generation (2014-2019)

    Learn how to troubleshoot and fix power window issues on Toyota Highlander (2014-2019). Step-by-step guide with diagnostic steps and repair instructions.

    Electrical5 symptoms

  5. how to fix P0171 in Toyota Highlander Third Generation (2014-2019)

    Learn how to diagnose and fix P0171 engine too lean condition in Toyota Highlander (2014-2019). Step-by-step guide with tools and repair instructions.

    P0171Engine6 symptoms

  6. how to fix the rear brakes on my Toyota Highlander Third Generation (2014-2019)

    Learn how to diagnose and fix rear brake issues on your 2014-2019 Toyota Highlander. Step-by-step guide with symptoms, tools, and repair instructions.

    Brakes5 symptoms

Share this solution

Comments

Sign in to share your thoughts

Sign In

No comments yet

Be the first to share your thoughts

Back to Generation