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Volvo engine code DTC P0421
Non–Methane Hydrocarbon (NMHC) Converting Calalyst: Conversion Efficiency Emission Threshold The Diesel Oxidation Catalyst (DOC) is constructed from a porous ceramic substrate coated in precious metals. It is used to oxidize fuel in the exhaust stream after the engine, and to generate an exotherm to assist in other EATS systems functionality, such as raising the temperature of the SCR during cold start conditions. The OBD monitor for the DOC consists of two separate system evaluations- one for the effectiveness of the DOC at oxidizing fuel actively dosed by the Aftertreatment Hydrocarbon Doser System during cold start up conditions, and another portion that runs when fuel dosing is not active, where an evaluation on the physical presence of the substrate is made. P0421 NMHC Catalyst: Missing Substrate DTC P0421 Component / System NMHC Catalyst - Missing Substrate Monitor Strategy Description Compare engine exhaust temperature rate of change to DOC temperature rate of change Fault Limit Ratio = Engine exhaust temperature rate of change DOC temperature rate of change < 1.5 Enable Conditions • Exhaust Gas Temperature Derivative > 3.75 °C/s or < -3.75 °C/s • Modeled DOC Outlet Temperature Derivative > 3.75 °C/s or < -3.75 °C/s • AHI Fuel Injection State Not Active • Number of sub evaluations 8 Disable Conditions No Active DTC's: • P2226, P2229, P0110, P0112, P0115, P0117, P20DD, P20E0, P229E, P2200, P0105, P0108; P2031, P2322, P2084, P242C, P242A, P242B, P0545, P0544, P2080, P1130, P1133, P20DC, P20D0, P20CF Time Required For DTC To Be Set 650 seconds (8 sub evaluations. 5 pass of 8 evaluations => PASS, 6 fail of 8 evaluations => FAIL) MIL Illumination 2 Drive Cycles