Some 2020 – 2024 model year Highlander and Highlander Hybrid vehicles may exhibit a condition in which the air conditioner does not cool due to a leak and/or corrosion in the rear underbody air conditioner tube and accessory assembly. The anti-corrosion material has been updated to reduce the possibility of this condition.
full bulletin at NHTSA ↗2021 Toyota Highlander electrical problems
moderate 20 complaints filed with NHTSA · avg repair $850 · see electrical across all vehicles →
Complaints
20
Recalls
0
Avg fix
$850
1fire
Is there a fix? Manufacturer service bulletins
The manufacturer has issued service bulletins covering electrical on this vehicle — documented repair instructions, service campaigns, or warranty extensions sent to dealers. A TSB isn't a recall (it's not a free safety remedy), but it's the manufacturer acknowledging the issue and how to fix it.
OBSOLETE NOTICE January 30, 2026: This bulletin is now obsolete. Please see T-SB-0001-26.
full bulletin at NHTSA ↗Some 2018 – 2024 model year Toyota vehicles equipped with a Premium Audio with Dynamic Navigation System require a Special Service Tool (SST) USB flash drive to update the map, points of interest, and system software.
full bulletin at NHTSA ↗Although the HV Floor Under Wire Harness and Rear Traction Motor Cable is covered by Toyota’s New Vehicle Limited Warranty for 3 years or 36,000 miles (whichever comes first), we at Toyota care about the customers’ ownership experience. Toyota is providing extended coverage under this Customer Support Program for repairs related to excessive corrosion to the wire harness connections at the Rear Motor Generator. Excessive corrosion can cause AM Radio Static during certain drive cycles, or the vehicle may not start.
full bulletin at NHTSA ↗The air conditioning dye injection tool kit has been developed to aid in identifying the location of air conditioning refrigerant leaks. The procedures outlined in this Service Bulletin aid in locating, inspecting, and repairing refrigerant leaks.
full bulletin at NHTSA ↗Source: NHTSA manufacturer communications. Bring the bulletin number to your dealer or shop.
The failure pattern owners describe
The 2021 Highlander shows a cluster of electrical problems spanning power loss, warning lights, and component failures. Most striking are sudden engine shutdowns—vehicles stalling at traffic stops or during highway driving with no warning, then refusing restart or showing phantom warning codes that disappear when scanned. One owner's vehicle became immobilized with stuck ignition and engaged parking brake; another experienced complete brake failure diagnosed to a wheel speed sensor.
Water intrusion emerges as a recurring issue after heavy rain: dashboard flashing, power windows stopping, and brake warnings appearing, then clearing once the vehicle dries. Toyota has declined deeper inspection or goodwill repair. Brake system malfunctions appear in multiple forms—unintended acceleration when braking applied, stuttering response, and braking power loss. Door lock actuators have failed in both front doors, leaving vehicles unable to lock remotely. The rear liftgate's hydraulic struts routinely fail right at warranty expiration, costing $1,000 to replace. One vehicle caught fire during a dealership test drive; Toyota's investigation concluded they were not liable but provided no report. Smaller but persistent complaints include sunroof glass spontaneously shattering, navigation display randomly flashing, battery leakage with smoke, and soy-based wire covering that allegedly attracts rodent damage. Dealers frequently lack root-cause diagnosis for warning light cascades, often clearing codes without finding underlying faults.
Same Toyota Highlander electrical reports on nearby years: 2018 · 2019 · 2020 · 2022 · 2023
Failure modes owners describe
Unintended Vehicle Shutdown and Immobilization
Vehicle shuts down without warning while driving or stalls at traffic stops (train crossing, red light), then will not restart or restart inconsistently. In some cases the vehicle becomes immobilized with power loss, inability to disengage parking brake, or ignition unable to fully power down.
When: Occurring on newer vehicles with low to moderate mileage (10,700 miles and 92,000 miles reported)
Symptoms owners cite: Sudden engine shutdown with no prior warning; Dashboard warning lights illuminating repeatedly (Reduced Engine Power, Brake System Malfunction, Pre-Collision System Malfunction, Parking Brake Unavailable); Vehicle becomes unresponsive or loses electrical power; Ignition stuck in 'On' position, unable to fully power off vehicle; Parking brake engages and cannot be disengaged; Power windows cease function; Multiple warning codes appearing after jump-start, then clearing with no error found on scan
Codes mentioned: Reduced Engine Power, Brake System Malfunction, Pre-Collision System Malfunction, Check Engine
Repairs/costs cited: Battery jump-started in one case; knock sensor suspected in another (though critter wire damage found instead); no recurring fix identified across complaints
Water Intrusion into Electrical Systems
After heavy rainfall, electrical systems malfunction including dashboard flashing, loss of power window functionality, and brake system warnings. Problem resolves once vehicle dries out, but returns with subsequent rain exposure. Suspected source is water intrusion through windshield cowl, firewall, or fuse box. Owner reports Toyota has issued service bulletins on other models for similar issues but refuses deeper inspection or goodwill repair on this complaint.
When: Occurs after heavy rainfall; 92,000 miles reported
Symptoms owners cite: Dashboard flashing and restarting after rain; Power windows stop working; Electronic parking brake fails to disengage; Systems return to normal once vehicle dries; Problem repeats with each rain event
Repairs/costs cited: Battery and alternator tested by dealership with no faults found; deeper water intrusion inspection refused by Toyota
Recalls/TSBs owners mention: Toyota Corporate refused goodwill repair approval and deeper inspection for water intrusion
Wire Damage from Rodent Chewing
Wires were chewed by rodents, causing multiple electrical warning lights. Dealership service manager stated that Toyota vehicles use a soy-based wire covering that allegedly attracts rodents. Multiple warning lights appeared despite the vehicle having no scan codes initially.
When: 10,700 miles, early in vehicle ownership
Symptoms owners cite: Reduced Engine Power warning light; Brake System Malfunction warning; Pre-Collision System Malfunction warning; Warning messages repeating after clearing
Repairs/costs cited: Suspected knock sensor initially, then critter wire damage discovered; further damage assessment pending
Brake System Failures
Braking system failures ranging from unexpected forward acceleration when brakes applied, to complete brake failure with non-responsive pedal. One owner reported wheel speed sensor failure causing brakes to fail entirely. Another complaint mentions low braking power warning and stuttering brake response.
When: Occurring at various mileages and driving conditions
Symptoms owners cite: Sudden forward acceleration when brake pedal applied; Vehicle does not slow down despite brake application; Stuttering brake response; Braking Power Low warning lights; Brake system described as failing completely
Codes mentioned: Wheel Speed Sensor fault, Braking Power Low
Repairs/costs cited: Wheel speed sensor diagnosed in one case; other cases lack specific repair information
Start/Stop System Malfunction and Power Loss
Start/stop system fails while vehicle waiting (at train crossing), engine cuts off and will not restart. Vehicle becomes stuck in ignition-on state with inability to power down completely without battery disconnection. Parking brake also engages and cannot be disengaged.
When: While vehicle stationary at train crossing
Symptoms owners cite: Engine shuts off via start/stop system; Engine fails to turn back over; Vehicle unable to shut off completely (ignition remains On); Lights remain on; AC display shows high power consumption warning; Parking brake engages automatically and cannot be disengaged; Parking Brake Unavailable message appears
Codes mentioned: Parking Brake Unavailable
Repairs/costs cited: Owner had to remove battery to reset vehicle; no repair information provided
Engine Check Light and Misfire Issues
Check Engine light illuminates repeatedly. Dealership attributed one instance to bad gasoline; however owner disputes this as problem should have occurred sooner if contaminated fuel was the cause. Warning lights return after dealer clears them with no underlying cause identified.
When: Early in ownership (3 days of purchasing vehicle)
Symptoms owners cite: Check Engine light illumination; Engine misfires reported by dealership; Warning light returns after being cleared
Codes mentioned: Check Engine
Repairs/costs cited: Dealership charged diagnostic fee and blamed owner for bad gasoline
Power Steering and Airbag System Warnings
Power steering malfunction and SRS airbag system malfunction warnings appear repeatedly. Initial attempt by dealership to reset the system; owner was instructed to unplug insurance tracker device suspected of causing electromagnetic interference. However, warnings recurred multiple times despite battery replacement.
When: First occurred 17 days after purchase, then recurred May 21 and May 28, 2021
Symptoms owners cite: Power Steering Malfunction warning; SRS Airbag System Malfunction warning; Warnings occurring at vehicle startup
Codes mentioned: Power Steering Malfunction, SRS Airbag System Malfunction
Repairs/costs cited: System reset attempted; insurance tracker device unplugged; battery replaced but issue persisted
Door Lock Actuator Failure
Both front door lock actuators failed, rendering vehicle unable to lock and disabling remote locking via Toyota mobile app. Owner states parts are difficult to source and repair is costly.
When: Not specified in complaint
Symptoms owners cite: Vehicle will not lock at all; Toyota app remote locking feature non-functional; Both front door lock actuators inoperative
Repairs/costs cited: Door lock actuators require replacement; parts scarce in market; repair costly
Rear Hatch/Liftgate Hydraulic Strut Failure
Rear hatch malfunction starting just as warranty was expiring (08/2024, three years). Hatch opens only partially or not at all, creating safety hazard when it stuck on dog's tail. Dealership reports seeing this issue frequently in other vehicles. Hydraulic struts require replacement.
When: At 3-year warranty expiration; worsened by January 2025 when strut replacement performed
Symptoms owners cite: Rear hatch opens only partially; Hatch sometimes fails to open at all; Hatch gets stuck in open/closed position; Hatch failure worsens over time
Repairs/costs cited: Hydraulic struts replacement required; cost $1,000 for service
Recalls/TSBs owners mention: Toyota customer service stated they do not track this type of failure
Trunk Malfunction
Trunk stops operating, producing loud beeping and failing to open automatically. Requires manual opening and closing with significant force to operate.
When: Not specified in complaint
Symptoms owners cite: Trunk fails to open automatically; Loud beeping from trunk; Trunk mechanism stuck, requiring manual force to open/close
Navigation Display Unit Failure
Navigation display randomly flashes and attempts to reboot but fails to power on. Creates driving distraction. Complaint mentions navigation system issues requiring multiple dealership visits and extended phone support.
When: Not specified in complaint
Symptoms owners cite: Navigation display randomly flashes; Display attempts repeated reboots; Display fails to power on fully; Creates driving distraction
Battery Failure and Leakage
Battery leaks fluid, produces smoke, and emits rotten smell. Electrical secondary brake system warning appears on dashboard.
When: Not specified in complaint
Symptoms owners cite: Battery leaking fluid; Smoke visible from battery; Rotten smell from battery; Electrical secondary brake system warning on dashboard
Codes mentioned: Electrical Secondary Brake System
Sunroof Glass Spontaneous Failure
Sunroof glass spontaneously shatters while vehicle is stationary at stop sign, producing sound like gunshot. Glass breaks in pattern described as 'volcano' with pieces facing upward. Dealership states vehicle is out of warranty and charges $1,450 for replacement. Owner believes this is manufacturing defect; reports finding hundreds of similar complaints online.
When: Not specified in complaint
Symptoms owners cite: Sunroof glass spontaneously shatters; Loud noise like gunshot during shattering; Glass breaks in upward-facing pattern
Repairs/costs cited: Sunroof replacement cost $1,450
Vehicle Fire During Dealership Test Drive
While at dealership for Check Engine light diagnosis, vehicle began smoking during test drive, then caught fire. Toyota Engineering Analysis fire inspection concluded Toyota was not involved in the fire, though vehicle was in dealership possession at time of fire.
When: August 2024, during dealership test drive
Symptoms owners cite: Loud bang during test drive; Smoke visible; Vehicle fire
Codes mentioned: Check Engine
Repairs/costs cited: Vehicle caught fire; dealership and Toyota investigation ongoing
Recalls/TSBs owners mention: Toyota Engineering Analysis inspection concluded Toyota not involved; dealership and Toyota not accepting responsibility
Wind Noise at Highway Speed
Loud wind noise occurs when vehicle reaches 40 MPH, described as sound like someone whistling into owner's ear. Dealership ordering part to address issue.
When: At speeds of 40 MPH and above
Symptoms owners cite: Loud whistling wind noise; Noise at highway speeds
Repairs/costs cited: Dealership ordering part to fix issue
Tire Pressure and Sensor Malfunction
Tire air/pressure issues and tire pressure sensors not functioning properly.
When: Not specified in complaint
Symptoms owners cite: Tire pressure sensor malfunction; Tire air/pressure issues
Blind Spot Monitoring System Failure
Blind spot monitoring system not responding or working properly on time.
When: Since vehicle acquisition
Symptoms owners cite: Blind spot monitoring not activating; Delayed or non-responsive blind spot alerts
Dashboard Malfunction
Dashboard not working properly; complaint mentions issues with display functionality.
When: Not specified in complaint
Symptoms owners cite: Dashboard display malfunction
Voice Dictation System Failure
Voice dictation system stopped working; owner can no longer send messages while driving.
When: Not specified in complaint
Symptoms owners cite: Voice dictation no longer functional; Unable to send messages via voice command
Synthesized from 20 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 0 most recent
Had electrical trouble with your 2021 Toyota Highlander?
File a complaint with NHTSA → It's free, official, and how every report above got here — owner filings are the federal safety record this page is built on.
Common questions
How serious is the electrical problem on the 2021 Toyota Highlander?
It's a documented issue but not catastrophic. 20 complaints have been filed. Repairs average $850 and most owners catch it before it causes a breakdown.
At what mileage does the electrical typically fail?
Based on the 20 complaints filed, electrical issues most often appear around 27,109 miles. Some report problems earlier; some make it well past 150,000 with no symptoms. Maintenance habits matter — vehicles that received timely fluid services and were not regularly overworked tend to last longer.
What does it cost to fix?
Independent shops typically charge around $850 for electrical repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to electrical?
No active recalls currently cover electrical issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.
Related
Complaint and recall data sourced from the National Highway Traffic Safety Administration (NHTSA)
public records database. Verify the raw federal record at
nhtsa.gov/vehicle/2021/Toyota/Highlander.
Severity ratings are derived from reported crashes, fires, injuries, and fatalities. Repair cost estimates are
independent-shop national averages and may differ in your area. Some links on this page are affiliate links.