Maruti Suzuki India on Tuesday reopened its Manesar plant amid tight security, according to media reports.
Maruti will start producing 150 cars a day instead of 1,500-1,700 units earlier.
The Manesar plant can produce 550,000 vehicles a year.
Maruti's Chief Operating Officer (Administration), S.Y. Siddiqui was quoted as saying that the company will operate just a single shift from 8 am to 4:30 pm.
At least 500 Rapid Action Force (RAF) personnel will guard the Manesar facility - 200 inside the premises and 300 outside - 100 in each shift. In addition, a force of 100 security guards comprising ex-servicemen, has been set up.
Forty personal security officers will look after the safety of managers, supervisors, and also workers, if necessary, according to Maruti.
A deadly riot prompted Maruti to shut the Manesar plant more than a month ago, and has cost the company more than US$250mn in lost output.
Maruti declared an indefinite lockout at Manesar on July 21 following the violence on July 18.
The lockout since July 18 has cost Maruti ~Rs 800mn a day. The company lost US$500mn in production in 2011 because of frequent labour unrest.
The July 18 violence killed a HR manager and injured more than 100 other employees.
Maruti has sacked 500 workers from the Manesar plant and abandoned its policy of hiring contract workers, reports said.