Theory of Operation

WARNING: This page is about a different car, the 2011 RAM Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

The Aftertreatment Diesel Oxidation Catalyst is designed to react with hydrocarbons in the exhaust stream, this chemical reaction reduces hydrocarbon emission levels and also produces heat. Periodically, the Powertrain Control Module (PCM) will utilize the heat generated by this reaction in the Aftertreatment Diesel Oxidation Catalyst to actively regenerate and clean the Aftertreatment Diesel Particulate Filter. This diagnostic checks that the Aftertreatment Diesel Oxidation Catalyst is present and functioning correctly. The PCM monitors the efficiency of the Aftertreatment Diesel Oxidation Catalyst for DD and DP models through interpretation of data received from the Aftertreatment Diesel Oxidation Catalyst inlet and Aftertreatment Diesel Particulate Filter inlet temperature sensor. For DJ and D2 models the DOC inlet temperature is calculated by the PCM, the monitor checks for a temperature rise across the Aftertreatment Diesel Oxidation Catalyst. The PCM will set the fault if it detects that the Aftertreatment Diesel Oxidation Catalyst is not present in the aftertreatment/exhaust system. The PCM will illuminate the MIL lamp when the monitor runs and fails in two consecutive trips. The PCM will turn off the MIL lamp immediately after the diagnostic runs and passes.