Common Reasons Trucks Fail Emissions Testing

1. OBD Test

The dreaded "check engine light" is the #1 reason vehicles fail emissions tests. Prior to inspection, ensure any engine codes are off and the dash is clear. Even if the light is just malfunctioning, this could be an electrical issue and will cause your vehicle to fail inspection.

If your vehicle isn't displaying any check engine lights and undergoes an emissions test, the VIR (Vehicle Inspection Report) will provide specific reported trouble codes. In the event of failure, we'll use these to diagnose and repair the vehicle's emissions systems.

2. Tail Pipe Test

Failing an emissions test due to exceeding tail pipe emissions limits can be due to an incorrect fuel mixture, malfunctioning Positive Crankcase Ventilation (PCV), ExhaustGas Recirculation (EGR) problems, vacuum leaks, incorrect ignition timing, malfunctioning oxygen sensors, or a clogged air filter.

In the event that any of these issues cause emissions test failure, our mechanics at Iron Buffalo Truck & Trailer can have the failure issue sorted quickly (often same day).

3. Vehicle Brakes

If the air brake valve isn't holding air pressure, the problem could result in a safety failure.

If your brakes or rotors are too worn or warped, damaged, or making concerning noises, they should definitely be serviced (but it might not cause failure). Additionally, ensure the master cylinder and wheel cylinder and in good working order as these are also common reasons vehicles fail inspection.

4. Vehicle Exhaust

In Colorado, almost any vehicle exhaust issues can cause emissions inspection failure. Ensure that your exhaust converter is funtioning and securely in place. Check the noise and smoke output to ensure they are not producing excessive amounts of hydro carbon and carbon monoxide. Exhaust leaks will be inspected as well and even small leaks can lead to emissions test failure.