I Failed The Emissions Test… Now What?

Your vehicle may have failed because it exceeded one or more of the allowable emissions limits established by the state for that vehicle. Or, it may have failed for visible smoke or missing emissions control equipment such as the catalytic converter, oxygen sensor, or gas cap.






The I/M 240 emissions test is designed to detect pollutants emitted from your vehicle under real-life operating conditions. You are responsible for making any necessary repairs to your vehicle before it is retested. Keep in mind that if your vehicle registration is due for renewal, it cannot be renewed without proof that the vehicle has passed the test or a waiver has been granted.

To find out why your vehicle failed, review the Vehicle Inspection Report given to you at the testing center. Test results are clearly documented under several key headings. To correct the problem, take this report to the repair technician of your choice. It will help in accurately diagnosing and repairing the problem. In most cases, simple corrections can be made to bring the vehicle into compliance and allow it to be successfully retested.

Getting Repairs
Take the vehicle and the Vehicle Inspection Report to a repair facility, like Gary's Auto Service. You may choose your own repair technician to perform the necessary adjustments or repairs. Once adjustments or repairs are completed, your repair technician must complete the back of the report before you return to the testing station.

Return the vehicle along with the completed Vehicle Repair Form on the back of your Vehicle Inspection Report to any of the 14 Air Care Colorado testing centers in the Denver/Boulder metro area for a retest. Once it passes, you will be able to renew your vehicle registration.

Remember, if your vehicle is repaired and retested at an Air Care Colorado station within 10 calendar days (not 10 business days) of failing the original test, the first retest is free. If the 10th calendar day lands on a Sunday or holiday when emissions centers are closed, the free test will be extended to the 11th day.
My vehicle failed its first emissions test. It passed a second test without getting any repairs. What gives? Is the testing equipment faulty? Are the test drivers to blame?

This situation is of concern to motorists, to the State of Colorado and to Envirotest Systems. Variable test results occasionally occur.

Test Lane Consistency
The emissions testing equipment is standardized in all of the I/M 240 emissions testing lanes. Each test lane self-checks every two hours. If this check reveals a problem with lane calibrations, the lane automatically shuts down, preventing inaccurate testing. In addition, computer software controls the dynamometer testing. The test driver cannot exert more than a marginal influence on the test results.

Vehicles are Variable
Variable test results are generally caused by the vehicle itself, and can happen for a number of reasons. The catalytic converter may not have been adequately preconditioned, or warmed up, for the first test. Driving a vehicle for at least 15 minutes or so to bring it up to operating temperature before taking it in for an emissions test is recommended, as cold vehicles emit a higher level of pollution. The vehicle may have switches and sensors that may be causing problems intermittently. This can be a particular problem with computer-controlled vehicles, and certainly can be a frustrating problem for repair technicians to diagnose.
Small differences in test results from test to test are normal for vehicles, particularly those that are computer-controlled. But if the vehicle is close to the pollution limits to begin with, a small difference in the test result can make the difference in failing or passing the emissions test.

The I/M 240 dynamometer test is very comprehensive. The vehicle is placed on the dynamometer, and the pollution emitted from the vehicle as it simulates driving down the road, accelerating, decelerating, and cruising is collected and analyzed. The idle test detects the pollution emitted only while a vehicle idles. Therefore, the I/M 240 test is much more likely than the idle test to detect an intermittent problem.

Intermittent Problems Can be Pain to Diagnose
Solving these intermittent vehicle problems sometimes requires real detective work by repair technicians. This is one of the reasons vehicle repair has become a much more high-tech business than it formerly was, and why continuing technician training is key to a repair shop's success. It is also why a diagnostic fee is a good investment.

The state is concerned about vehicle variability because a vehicle that manages to pass the emissions test but still goes unrepaired continues to pollute significantly more than it should. The Colorado Air Pollution Control Division maintains several Emissions Technical Centers around the Denver-Boulder area for the purpose of helping motorists diagnose difficult vehicle emissions problems. They may be contacted at 303-744-2442 (and press 3) for information or an appointment.

My Vehicle "Check Engine" Light Advisory Failed. What does this have to do with emissions?

Potentially, a lot. When a vehicle's "check engine" light is on, it usually is an indication of significant problems with the emissions control system and/or other systems detected by the vehicle's onboard computer.

Effective April 1, 2003, an illuminated "check engine" light is no longer a mandatory pass/fail component of the emissions testing process. If the "check engine" light is illuminated, it is noted on the vehicle inspection report each motorist receives at the end of the emissions testing procedure. However, it is an informational tool for the motorist, rather than a reason for failure.

Inspection of the "check engine" light is meant to protect you - the motorist - and Colorado's air quality. Although the emissions testing cycle can be completed, the light can indicate problems with the vehicle. If problems associated with the "check engine" light are not diagnosed in a timely fashion, costly repairs may be waiting down the road. If properly diagnosed and repaired, your vehicle may experience improved emissions, drivability and fuel economy.

In many instances, repairs or replacement of certain emissions control components are covered under the manufacturer's warranty . However, failure to maintain your vehicle (including necessary maintenance when a "check engine" light indicates a problem) may void the warranty.

So, if your "check engine" light is lit when it's not supposed to be, your vehicle may be trying to tell you something. Do yourself a favor and have it checked out by a good repair technician. Your vehicle (and your wallet) will thank you.