How Can I Prepare For an Emissions Test?

Annual emissions testing is required in order to ensure that your car is not producing too much pollution and that your emissions control components are in working order. While not all areas of the US require emissions testing yet, those that don’t are becoming rarer. If your car doesn’t pass the emissions test, you’ll be on the hook for repairs and parts replacement required to get it to pass, or you might face fines, fees or other consequences. How do you prepare for an emissions test?

Check Engine Light

First and foremost, if your Check Engine Light is on, your car won’t pass the test. It’s as simple as that. Have the code pulled, and then make the repairs needed. Chances are good it’s something simple, like a damaged spark plug wire, or maybe a damaged gas cap seal or a failed oxygen sensor. Take care of any Check Engine Light related issues before going for your test. You’ll also need to drive the car for a few days after having the Check Engine Light cleared, as part of the test looks at computer history for the vehicle.

Drive it

One complication that can arise with your test is if your OBD (on-board diagnostics) system is “not ready” for testing. This can happen if the system hasn’t been operated long enough to conduct all of its self-checks. Your car won’t fail, but you’ll be declined and have to retest on another day. The best way around this is to drive your car for at least 20 miles before going to the testing station.

Air filter

Correct airflow into the engine is critical for emissions, and if your air filter is seriously clogged, it can affect your emissions test results. Change your air filter before the test to make sure that your engine has a steady stream of fresh air for combustion.

Don’t turn off the engine

While you’re waiting for the test at the testing station, keep your engine running. Turn off things like your air conditioner or heater, but leave the engine running with the car in park. This will keep the operating temperature in the normal range (your engine can’t be tested if the exhaust system is too cool).

The best advice is to simply have your car tested, and then make any necessary repairs afterwards. The re-test should be free of charge if done within the window allotted by your state government.


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

How to Replace an Exhaust Clamp
An exhaust pipe is supported by exhaust clamps within a vehicle. A bad clamp can lead to exhaust leaks that can turn hazardous if not addressed.
How to Replace an Exhaust Manifold
Exhaust manifolds remove exhaust gas during the exhaust stroke. Engine performance issues and engine noise are signs to replace the exhaust manifold.
3 Reasons Your Car Smells like Rotten Eggs
A sulfuric or rotten eggs smell indicates an excess of byproducts left over from failed combustion. Removing the smell requires part replacement.

Related questions

Water blowing out tailpipe.
The first thing I would have to ask is if the cooling system is getting low on coolant. Does the engine run rough or misfire? The water coming out of your tail pipe may be just that, water due to...
I brought a 2006 Infiniti g35 coupe. When I start it up it sounds like a race car, when I press the gas it gets louder until I let
The previous owner might have modified the air intake (a box like component holds the intake filter) but the noise you are referring to is probably caused by a defective exhaust and/or aftermarket exhaust parts which result in excessive noise....
I have a 2002 nissan sentra 1.8 I'm trying to find the best place to purchase a front and rear catlyic converter
For the amount of the converters you will be best served purchasing the parts at local auto parts store so you have a place to go to get any warranty adjustments done. If you live in a state that regulates...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com