OBD II Fault Code

  • OBD II P20EF

    OBD-II Code Diagonostic Trouble Code is defined as a SCR nox Pre- Catalyst Efficiency Below Threshold

    Diesel Exhaust Fluid (DEF) is used to assist in converting leftover exhaust particles to harmless gases. In order to burn off those particles, the temperature of the exhaust system needs to increase. the injection of DEF Fluid into the exhaust stream brings Diesel Particulate Filter (DPF) up to temperature. The system is then able to convert harmful NOx to Nitrogen, Carbon Dioxide, and water. The Reductant Catalyst (SRC) was added to further reduce any NOx was still in the exhaust stream. The engine computer (PCM) monitors the Reductant Catalyst System's use of DEF and its ability to convert NOx to Nitrogen, Carbon Dioxide, and Water. If the Reductant Catalyst fails to perform its job efficiently, code P20EF is set.

    Diagonostic Trouble Code Symptoms

    • DPF regeneration may not occur

    Common Problems That Trigger the P20EF Code

    • DEF contamination
    • DEF injector failure
    • Selective Catalytic Reduction (SCR) failure

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