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Home >> Ford >> 2002 >> Cutaway 7.3 F >> Repair and Diagnosis >> External Pages >> Different car >> Section 2376 (Engine Controls - Diagnostic Subroutines - 6.4L 99R Diesel -- F250-F550 Super Duty) >> Diagnostic Trouble Code (DTC) Charts and Descriptions >> P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

P0420 - Catalyst System Efficiency Below Threshold (Bank 1)

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P0420 - CATALYST SYSTEM EFFICIENCY BELOW THRESHOLD (BANK 1)

Description:  The powertrain control module (PCM) monitors the exhaust gas temperature (EGT) sensors to determine if a concern is present with the oxidation catalytic converter (OC). During a regeneration, when the soot in the OC is reduced to ash, the PCM expects the temperature across the OC to increase by a calibrated amount. The test fails when the increase in temperature is less than 25% of the expected maximum increase.
Possible Causes: 
  • Fuel injection concern
  • Fuel quality
  • Plugged OC
  • Oil contamination
  • Damaged OC
Diagnostic Aids:  Verify there are no concerns present with the fuel system and EGT sensors. Monitor the EGT11 and EGT12 PIDs to determine the temperature change across the OC.
Application    Key On Engine Off  Key On Engine Running  Continuous Memory 
All   - - refer to PINPOINT TEST RA .