Exhaust Catalyst and Exhaust System: Notes

The exhaust catalyst and exhaust system consists of the following components. For additional component information, refer to ENGINE CONTROL COMPONENTS  in this service information.

• Four exhaust gas temperature (EGT) sensors that measure the exhaust gas temperature.
• An oxidation catalytic converter (OC) that reduces emissions and assists in diesel particulate filter regeneration.
• A selective catalytic reduction (SCR) catalyst that chemically reduces nitrogen oxides (NOx) to nitrogen (N₂ ) and water (H₂ O).
• A reductant injector that sprays diesel exhaust fluid (DEF) into the exhaust system as a component of the NOx reduction reaction.
• A diesel particulate filter pressure sensor measures the gauge pressure of the exhaust gas before the diesel particulate filter.
• A diesel particulate filter that traps soot and ash particulates.
• A particulate matter (PM) sensor that monitors soot levels downstream of the diesel particulate filter.
• Two NOx sensors that detect levels of NOx in the exhaust stream, to monitor SCR efficiency.