A second Volkswagen diesel engine sold in Canada may have been fitted with software to cheat on emissions tests, the company revealed on Thursday.

VW had previously admitted that the software was installed on cars with the EA 189 diesel engine built to the "Euro 5" emissions standard.

The company is now checking whether older models with the EA 288 diesel motor built to the same emissions standard may also have the software, a spokesman said. The 2.0-litre, four-cylinder engine was introduced in 2012.

A Volkswagen Canada spokesman said cars with this engine are being tested by regulators here for the "cheat device," which switches on emissions controls for nitrogen oxide in testing conditions but switches them off during real-world driving.  

The vehicles equipped with this engine have been under a stop-sale notice in Canada since Sept. 21 and will remain so until a resolution is found, the VW Canada spokesman said.

There is as yet no timetable for a recall, he added.

U.S. cars affected, but not EU vehicles

They were included in the original count of affected Volkswagen products issued by Environment Canada, which amounted to more than 100,000 cars.

Volkswagen says as many as 70,000 U.S. vehicles may have the EA 288 engine, but it believes vehicles sold in Europe do not have the software.

Until now, the scandal has been centred on the EA 189 diesel engine, a four-cylinder engine introduced in 2009 which is known to have the software.

The Euro 5 emissions standards, implemented in 2009, set emissions levels for European cars and light trucks. The Volkswagen emissions scandal has revealed the degree to which North American regulators relied on the EU to test diesel engines.

Diesel engines generally have lower carbon emissions than gasoline engines, but higher emissions of particulates and nitrogen oxide, which can cause smog and contribute to asthma and respiratory problems.