Ontario’s auditor general has questioned the effectiveness of the province’s emissions testing program leading Conservatives to call the Drive Clean program "redundant."

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Ottawa mechanic Lloyd Gilchrist says there has been a large jump in failed emissions test since the new on-board diagnostic method came into effect in 2013. (Stu Mills/CBC)

As of Jan. 1, emissions testing in Ontario changed and began using the on-board diagnostic testing method instead of the old method of measuring exhaust emissions straight from the tailpipe.

The new form of testing only tests vehicles built in 1998 or later. Vehicles built between 1988 and 1997, which experience a failure rate between 11 and 31 per cent, are still tested using the "two-speed idle method."

Mechanics have told CBC News half of the vehicles they see fail the new test due to problems with the vehicle's computer, which are not due to emissions problems.

Many of the mechanics, including Lloyd Gilchrist, are struggling with the new Drive Clean emissions test due to circumstances that lead to a reboot of the system.

He said about seven of every 10 vehicles he has tested in 2013 have failed.

"I think (the government) should have tested it a bit longer before they brought it out to get all of the bugs out of it," Gilchrist, who has been testing Honda vehicles for a decade, told the CBC's Stu Mills.

Emissions tests not reason for better results, AG says

The province's auditor general, Jim McCarter, said "the reduction in vehicle emissions in Ontario is due largely to factors other than the program," which was featured as part of his 2012 annual report.

McCarter credited "better manufacturing standards for emission-control equipment and federal requirements for cleaner fuel" for a decline in failed tests.

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PC environment critic Michael Harris is accusing the government of changing the emissions testing method to spike the number of failed tests. (Supplied photo)

He added it might not make sense to charge drivers $30 million per year when the failure rate is as low as reported.

The PC environment critic, MPP Michael Harris, also said a report on vehicles tested between 1998 and 2010 shows only five per cent of vehicle's emissions are too hazardous to pass a test. The report was conducted for the Ministry of Environment by a firm in Vancouver.

At the turn of the millennium, about 16 per cent of vehicles failed an emissions test.

Ontario Environment Minister Jim Bradley was not available for comment.

The Drive Clean test is only necessary for vehicles travelling as north as Ottawa and as south as Windsor. Some drivers told CBC News they register their vehicle and licence plates in areas such as Timmins, in northern Ontario to avoid the emissions test.

5 steps to make your vehicle ready for a Drive Clean test

1. Make sure the vehicle has been parked for eight hours without a start.

2. Start the engine and allow it to idle in Drive for two minutes and 30 seconds with the air conditioning and rear defroster on.

3. Turn the air conditioner and rear defroster off. Drive the vehicle for 10 minutes at highway speeds.

4. Drive the vehicle for 20 minutes in stop-and-go traffic.

5. Go to your test.

With files from the CBC's Stu Mills