Economic Times has reported that General Motors India, the Indian arm of the Detroit-headquartered automaker, has admitted to the government that an internal probe had revealed the company violated testing norms and its employees re-fitted already approved engines in new Tavera models sent for inspection in order to meet specified emission norms. 
In a letter to the government on July 18, GM India said it had suspended production and sales of two Tavera variants after it 'discovered' compliance failures.

The report mentions that GM India's letter addressed to various government ministries and departments states, "Recently, the company has discovered information that it wishes to report to you...investigations initiated by the company have revealed that over a period of time some employees of the company engaged in the practice of identifying engines with lower emission which were fine-tuned and kept aside to be used for installation on vehicles during inspection."
 

Read the complete ET report here