This system includes any device used to control emissions measured at the tail pipe. The emission control system is very simple due to the very precise control of air/fuel mixture that fuel injection provides. Components include the catalytic converters and the Exhaust Gas Recirculation (EGR) valve and controls. The EGR system uses a poppet type valve to regulate the amount of exhaust gas flowing into the intake manifold.
When servicing or repairing any part of the emissions system, it is absolutely essential to check for any obvious mechanical faults or failures. Remember, a trouble code only indicates which sensor or circuit is affected by the problem. Simple mechanical faults such as a vacuum leak or poor electrical connection can cause a fault code.