DIESEL TESTING
As part of the MOT test your vehicle will be checked for smoke emissions. This helps the environment by minimising pollution and testing the fuel efficiency of your vehicle. It also helps you by checking that the engine is working correctly and reduces wasted fuel.

HOW DIESEL EMISSIONS ARE TESTED
The test has been developed so that it should not damage your engine. The tester will check the maintenance history of your vehicle by asking you some questions. The tester must refuse to test your vehicle if he thinks that the smoke test will damage your engine.

PLEASE TELL THE TESTER IF YOU THINK THE SMOKE TEST MAY DAMAGE YOUR ENGINE

To reduce the possibility of damage and increase the chances of passing you should:

• Keep your vehicle maintained at all times
• Have the camshaft drive belt replaced at the recommended intervals
• Go for the test with a fully warmed up engine - it will produce less smoke and is safer to test
• Do not tamper with governor settings. They have been set to help ensure the engine runs efficiently

THE TEST
After checking the oil temperature to ensure the engine is warm, the tester will accelerate the engine from idle until the governor cuts in a maximum of 6 times. Your engine will not be held at full speed for any length of time. If your engine has been maintained, the test should not cause any damage to your engine