2021 Toyota Highlander Electrical Problems

Mileage when the problem started

Owner reports

Selected complaints filed with NHTSA by 2021 Toyota Highlander owners, lightly cleaned up (personal details are redacted by NHTSA).

The Check Engine light came on and I took it into Toyota of Downtown dealership where I was receiving periodic maintenance. After 2 days, they said the light was out but they hadn't found the cause. I could either leave if for a few more days or take it and bring it back if the light came on again. This was early August. I chose to take the car & when the Check Engine warning light came on again, I took it in on Aug 15, 2024 before I left to Portland to give them more time. I returned on Monday & couldn't reach them. The next day they informed me that while on a test drive, there was a loud bang, it started smoking and by the time 911 arrived it was on fire. After a 2 month investigation by Toyota's Engineering Analysis fire inspection, they concluded Toyota was not involved. …

The contact owns a 2021 Toyota Highlander. While driving 20 MPH uphill, the messages "Engine Failure," "Brake Failure," and "Pull Over to A Safe Place, See Owner's Manual" were displayed, and several unknown warning lights illuminated. The contact turned off and restarted the vehicle, but the failure persisted. After a second restart, the message "See Dealer" was displayed with the check engine warning light illuminated. After a third restart, the vehicle was driving rough while the accelerator pedal was depressed. The vehicle was taken to the dealer. The manufacturer was notified of the failure by phone. The failure mileage was approximately 123,000.

On August 24, 2026, my vehicle was parked, turned off, and locked for more than 6 hours in a parking lot. Without warning, the vehicle experienced a spontaneous thermal event/self combustion. The fire and thermal damage were entirely localized to the dashboard area inside the passenger cabin. The engine compartment, battery area and front mechanical components remained completely unaffected by the fire. The vehicle was off, motor was cold and car was closed and parked for about 6 hours when this incident occurred.

Vehicle was driving at highway speed, transitioning to off ramp. Warning lights came on stating Braking Power low. Brakes proceeded to fail. Stepping on brakes did nothing but initiate a stuttering response. Vehicle would not slow down. Rolled into dealership that was luckily .5 miles away. It was diagnosed to be a wheel speed sensor. A sensor failing should not cause a vehicle to be unable to brake. Shocked and traumatized over the incident.

We rented this vehicle from Avis at Detroit Metropolitan Airport on Tuesday, 11/22/22 at approx. 7:50 pm. It was raining, cold and temperature was dropping. We drove approx. 1/8 to 1/4 of a mile from the facility. As we turned left on to a major roadway (Goddard) southbound, I turned on the rear defroster. Suddenly, the engine went into limp mode. I tried to make a U-turn to drive back to the facility. Engine lights flashed (low oil pressure, check engine, etc) and then the engine stopped. We barely had enough power to turn the vehicle out of the turn lane before we would have been struck by a bus. We sat in left northbound lane of Goddard for approx. 2 min without our hazard lights on. The vehicle would not start. I then pressed the defroster again and the engine fired up. We drove back to the facility and demanded a new vehicle. …

[redacted], while driving on a [redacted], my 2021 Highlander Platinum unexpectedly shut down without ANY prior warning or indication of a malfunction. This abrupt failure put my safety, as well as that of my passengers and other motorists, at considerable risk. As a longtime Toyota customer, I have always valued the reputation of Toyota vehicles for their reliability and safety. However, this incident has significantly shaken my confidence in that reputation. I trusted that my vehicle, particularly one as recent as the 2021 Highlander, would perform safely and effectively in all driving conditions. The complete and sudden failure of the vehicle on a busy highway is not only unacceptable, but also alarming. I now find myself questioning whether I can continue to rely on this vehicle or the brand itself. …

Vehicle: 2021 Toyota Highlander XSE Approximate Mileage: 92,000 Location: Boerne, TX (Texas Hill Country) Summary of the Problem: My vehicle experienced serious electrical failure after heavy rainfall in the Texas Hill Country, where catastrophic flooding recently occurred. At a red light, the dashboard began flashing, power windows stopped working, and the electronic parking brake would not disengage. I was nearly rear-ended with my children in the car because the vehicle temporarily lost responsiveness. Pattern of Issue: This problem only occurs after rain. Once the vehicle dries out, the systems return to normal. Toyota tested the battery and alternator and found no faults. …

The vehicle experienced a transmission failure at approximately 62,000 miles, which required a transmission replacement. Toyota replaced the transmission with a rebuilt transmission. Immediately after the repair, the vehicle began experiencing multiple issues that were not present prior to the repair. The vehicle initially would not reverse, and the battery was drained shortly after the repair was completed. Following the repair, the vehicle has continued to experience ongoing electrical malfunctions, including dashboard warning lights, system alerts, and dash lights flashing during remote start. The vehicle has also developed a rattling noise underneath the vehicle. The exact failed component has not been clearly identified. The dealership has provided changing diagnoses and has not provided written diagnostic documentation despite requests. …

On February 16, 2025 the vehicle was parked. The temperatures that day were in single digits. After approximately 1 1/2 hours the 12V system was drained. The driver panel was blank and the vehicle did not respond to any attempt to start. This vehicle had a similar incident the prior year, also in extreme cold conditions. During that incident the vehicle was towed to the dealership. They recharge the 12V system and did not find any problems once the faults were cleared. For the February incident, an attempt was made to jump start the vehicle. After the jump start the driver panel was active, but the vehicle reported a hybrid system malfunction and would not start the engine. The vehicle was then towed to the dealership. Attached is the report from service team. Problem #1. …

Upon starting my 2021 Highlander Platinum with 10,700 miles on it several warning lights repeatedly came across my display including reduced engine power, brake system malfunction, pre collision system malfunction. See your dealer. No codes showed up on their scan but every time they cleared the screen the messages came back. They decided it was a bad knock sensor. Then I received a call that a critter had chewed wires and they might find further damage. I was surprised because I've been in my house for 45 years and I've never had a critter in my garage. The service manager said "Toyotas attract critters because of the covering they use on the wires." I said, "Soy?" And he said, "Yes". So, isn't this a manufacturing defect? How many times a year is this going to happen? I've owned Toyotas for 27 years. I've never had a problem until this car. …

Electrical complaints in other Highlander years