Auto major Tata Motors will be replacing the starter motor on all the Nanos - some 140,000 of them - sold till November, for free.
The move didn't stem from a safety fear but was a replacement being offered to customers to enhance the car's performance, the company said.
A starter motor is an electric motor that helps in rotating the internal combustion engine that powers the car. A better motor means a more responsive car.
"No complaint has been received and hence it is not a recall. It is only an upgrade," a Tata spokesperson said.
The new motor comes fitted with the Nano's 2012 version, which went on sale in November, and is being offered to around 140,000 customers, making it the country's biggest replacement exercise.
The "upgrade", which began in October, is to cost around Rs 110 crore, though the company refused to share details. This is the second time in Nano's 30-month life that the company has offered to replace or add components to the world's cheapest car - a basic model costs Rs 1.4 lakh - at no cost to the customer.
In November 2010, Tata offered additional safety equipment to the owners after some cars reported fire.