P0420

DTC P0420 Catalyst System Low Efficiency

Description

The ECM reads the exhaust gas temperature during the DPF regeneration event. If the ECM detects that the exhaust gas temperature is not within a predetermined range of the calculated value this DTC will set.

Condition for Running the DTC

^ The battery voltage is between 10 and 16 volts.
^ The ignition switch is ON.
^ The engine is running.
^ The engine speed is between 1400 and 2400 RPM.
^ The fuel injection quantity is between 30 and 100 mm3/stroke.

Condition for Setting the DTC

^ The ECM detects that the exhaust gas temperature 2 is lower than a threshold range.

Action Taken When the DTC Sets

^ The ECM illuminates the MIL when the diagnostic runs and fails. Refer to DTC Type Definitions for Action Taken When the DTC Sets - Type A.
^ The ECM inhibits EGR control.
^ The ECM inhibits cruise control.

Condition for Clearing the DTC

^ Refer to DTC Type Definitions for Condition for Clearing the MIL/DTC - Type A.

Diagnostic Aids

^ If an intermittent condition is suspected refer to Intermittent Conditions in this section.
^ Use the Temperature vs. Resistance table to test the EGT sensor 1 or 2 at various temperature levels to evaluate the possibility of a skewed sensor.

Circuit/System Testing DTC P0420