Failed Emissions Test

Never have your vehicle emission tested if your check engine light is on.  If the check engine light is off and your vehicle is newer than 1990, then you should be able to pass the emissions testing.  If your check engine light is on and you are due for an emission testing, then call us to schedule an appointment to diagnose the check engine light.  Once we repair the failing component that is causing the check engine light then you should be able to pass emissions testing without any difficulty.  However, your vehicle may have to go through its computer processes to determine all is well with your vehicle and that can take time.  Make sure you check with us when it is ok to go through emissions testing.   Your car’s emissions system not only allows your engine to function properly, but also protects you from the harmful emitted by the engine, such as the exhaust. The most common problems with the emissions systems are problems with your EGR valve, oxygen sensor or catalytic converter needing repairs. If your vehicle has emission problems, it can also impact vehicle performance and should be taken seriously.  A vehicle with a failing exhaust system will fail emissions and consequently be illegal to drive.  We have extensive experience fixing emissions related problems and can usually diagnose in a short period of time. 


Oddly enough, the first thing to cause a check engine light on most vehicles is the gas cap.  The vehicle’s computer monitors the gas tank pressure and a dried-out seal on a gas cap will let out fumes and thus cause a check engine light.  Other components we see next are EGR valves, charcoal canisters, catalytic converters, O2 sensors and exhaust leaks.  Signs that you need something emissions related repaired or replaced on your vehicle:

  1. Rough idle
  2. Noticeable reduction in engine performance
  3. Check Engine light on.
  4. Intermittent stalling.
  5. Smell of fumes in or outside of the vehicle.


You should not drive with many emission related problems.  The key is knowing what part is failing and we can advise you if it is ok to drive and for how long.  But keep in mind the repair will have to be done in order to pass emissions testing.  Driving with malfunctioning emissions systems can be against the law, hazardous to your health and the vehicles well-being. 


Usually the only thing you can do yourself is replace the gas cap which is usually the first thing to go on the emissions system and cause a check engine light.  Most of the components however require someone that is skilled in the repair.  There are many other complexities to emissions testing that can cause a nightmare experience if you are not properly trained.  Sometimes the computer doesn’t like certain aftermarket replacement parts or certain grounding wires and O2 Sensors don’t work well together.  The biggest obstacle is the computer on your vehicle can take weeks to determine if it likes the repairs you did.  If it doesn’t like the replacement parts, guess what?  Check engine light comes back on.