Tata EV Owners Struggle With Persistent ‘Critical’ Errors, Solutions Elusive

Mumbai-based Gaganpreet Singh received a rude shock on a Friday morning in June when his Tata Tiago EV stalled on the highway, on his way to work. The car, which was at 88% state of charge (SOC) at the time, started flashing a “high voltage critical error” sign and switched from ‘drive’ to ‘neutral’ mode. Fortunately, when he restarted the car, the sign had disappeared.

Singh, who bought the car in January this year, said this was the first time he had faced the HV critical error issue, but he was already aware of it. That’s because scores of Tata Motors’ electric vehicle (EV) users have complained of the persistent HV critical error which causes their cars to stall, leaving many stranded. This issue often disappears after restarting the car but frequently recurs, leading to multiple battery and component replacements for some users. Despite Tata Motors’ significant share in India’s EV market, the company’s lack of clear communication and solutions has left many users frustrated and seeking answers.

The Core spoke to 15 Tata EV users across the country – owners of the Nexon and Tiago EVs primarily who have faced the issue at varying degrees and for various reasons. What is clear across the board is that there is no clarity on what causes the error to flash in their cars, how to prevent it, and no solid information from either the original equipment manufacturer (OEM) or dealerships.

What Is The High Voltage Critical Error?

Think of it as the ‘check engine’ light in a petrol/diesel car or as the blue screen on a Windows computer. “It is a fail-safe mechanism,” a technician at a Tata service centre in Mumbai told The Core. The electric car runs on a high-voltage battery system, and the critical error flashes in cases where there is an issue with the car’s sensors or the battery pack itself.

Many users reported that the critical error flashed when their battery state of charge dropped below 10%, however, this is not always the case. Another service centre advisor told The Core that when all the cells in the battery pack are not equally discharged, this causes the battery to rapidly deplete and could lead to an error. The HV critical error can also show up when there are issues with charging at public fast-charging facilities.

In many cases, simply switching the car off and leaving it for a few minutes is enough to fix the problem. A Mumbai-based Nexon EV user told The Core that he had faced the error twice, and since he was aware of this, he turned it off and left it for about 20 minutes. After this, it was resolved.

This isn’t always the case though. Many users have had to make frequent trips to the service centre, and have had components replaced. Of the 15 people The Core spoke to, five have had their batteries replaced, and one user had it replaced twice in two years.

It must be noted that the high voltage critical error isn’t just a Tata problem. It has cropped up in MG Motor EVs, as well as in Tesla cars abroad. However, instances in MG cars are relatively fewer. Plus, two EV users who own both Tata and MG EVs (one in Delhi and one in Bengaluru) told The Core that the issue had been resolved fairly quickly, without recurrence, in their MG cars.

Given that Tata Motors currently sits on the largest chunk of India’s electric car market (at a 73% share), it might explain the larger number of user complaints for Tata cars. However, what is glaring is the company’s silence and lack of explanation in such cases.

Most of the information about how to deal with errors at an individual level is dispensed by more experienced EV users who run community channels and forums on social media. Requests for official information on battery health or causes for the error are often rejected by the company and dealerships. Even suggestions on how to best avoid the error seem to be scattered.

In a written response to The Core, Anand Kulkarni, chief products officer and head of HV programs and customer service, Tata Passenger Electric Mobility Ltd. said that the company has observed the prompt appearing mostly when there is an irregular charging pattern. "Through our outreach to customers via multiple channels like social media, YouTube, and on-ground awareness sessions, we have constantly explained the importance of maintaining a regular cycle between fast and slow charging, where we recommend a certain pattern to maintain a healthy battery," he said, adding that the company is sharing tips on charging on its YouTube channel to educate users. 

"To resolve issues like these – our colleagues in the sales and service function constantly endeavour towards educating customers for deeper penetration of information. Furthermore, our customer support teams are equipped with hands-on training, where they are taught to help customers find the quickest possible solution when faced with this error," he added. 

How It Affects Users

The lack of effective solutions for the error seriously hampers the day-to-day use for owners. For instance, Chennai-based Ram Kumar, a Nexon EV owner, purchased the car second-hand from a friend, and was aware of the car facing the HV critical error periodically. He visited the service centre twice, and was told it was an issue related to his BMS. But they could not properly resolve the solution. The critical error appeared mostly when the charge dropped below 25%, "and they didn't even test the car below that," he said. “I don’t let it drop below 25% now,” he said.

Similarly, several users recounted how they don’t let their cars’ charges drop below a certain level.

Mumbai and Delhi-based Priyans Murarka has had his car in the service centre for over three months now. He faced the HV critical error issue in his Tiago EV four times since he purchased it in 2023. After the third instance in October 2023, the service centre replaced his battery management system. However, the error reappeared in March this year.

He took it back to a Mumbai-based authorised service centre, where they told him his battery pack would have to be replaced. “I asked them to give it to me in writing that they were replacing my battery pack,” he said. This was because it was unclear whether the company was replacing the entire battery pack, or simply repairing it. Murarka also asked for the state of health (which indicates the level of degradation and remaining capacity) of the battery. But the centre refused to give them to him in writing.

Since then, they have been locked in a battle as Murarka refuses to accept the car without a written record. With the issue not anywhere close to being resolved, Murarka said he is preparing to take a legal course.

Two other users told The Core that they had asked for the state of health of their replaced batteries and had been refused.

Not Just Private Users

The HV critical error has also cropped up in commercial fleets as well. A large-scale fleet operator, who works with ride-hailing services, who did not want to be named, told The Core that they had observed the error in some of their Tata EVs. The company has identified the primary cause to be battery cell imbalance due to frequent fast charging, as well as overheating and issues with AC components.

They added that they were working with the company to address their issues and work on resolving them.

No Concrete Information

The HV critical error can be caused by a host of issues. What complicates the matter is the lack of a concrete diagnosis. Service centres appear to be ill-equipped to resolve the issue.

“Everyone has a different thing to say about why this error occurred. I got three versions of advice from one service centre, that’s how skewed and unpredictable it is,” another user, who faced the issue when his battery charge dropped below 8% told this reporter on X.

Similarly, another user from Bengaluru said that he had been recommended by the dealership to let his battery charge drop below 10% and then slow charge it to 100% at least once a month. He had been following this religiously until he faced the HV critical error and his car stalled. “At the service centre, they inquired as to who advised us to take the car to less than 10%. When I told them that it was the dealership they were flabbergasted,” he said. “In all honesty, I doubt they understood the error and just thought that it was because the battery level was so low.”

On the other hand, service technicians mainly blamed user behaviour. An EV technician The Core spoke to said that users don’t follow the recommended charging methods, fast charging more than needed. This causes cell imbalance, which causes the error, he said. The other reason is faulty hardware, in which case the company replaces it under warranty.

Of the about 15 cars that come into his service centre each month, 3-4 need battery repairs or replacements. “A few months back, we had 10 replacement orders,” he added.

What About New EVs?

The service technician added that they have seen fewer battery issues recently and claimed that the company was making adjustments.

Tata Motors gets its EV batteries from Tata Autocomp, Tata Group’s automotive component manufacturing arm. Tata Autocomp, in turn, assembles battery packs with cells and battery management systems sourced from Chinese manufacturer Gotion China.

The service technician added that the company had managed to mitigate the HV critical error in its newest offering - the Tata Punch EV, which uses a different battery system. The Punch EV’s battery was designed first, and the body was built around it, imbibing a “pure EV” architecture. However, complaints have started surfacing on social media from Punch EV owners as well. The Core could not independently verify whether Tata has ironed out the issue in the newer models.

Editor's Note: This article was updated with responses from Tata Motors after publishing.