Lou's Diagnoses That Check Engine Light FOR FREE!Since 1995, all vehicles have been equipped with an OBDII port, in which you can use a scan tool/code reader to see what is wrong with your vehicle. The ECU or Computer in your vehicle is actually receiving data from a variety of different sensors to make sure everything is working properly and in sync.Even if the code may not be exhaust related, Lou's Custom Exhaust can still scan the computer's codes on your vehicle free of charge and fairly quickly.The most common codes seen are the catalytic converter low efficiency (P0420) and EVAP codes (Leak in the evaporative emissions system).Once the problem is fixed, the code can then be erased, but it may take some driving time before the computer will recognize it's actually fixed, in which case the system is pending.So swing by any one of our 4 locations:Hyannis 508-771-2500Plymouth 508-746-3500Quincy 617-773-6500Westport 508-646-1500