OBD II Fault Code

  • OBD II P20B9

    OBD-II Code Wiring issue is defined as a Reductant Heater "A" Control Circuit/Open

    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 Reductant Heater warms the Reductant (DEF) tank to prevent crystallization of the DEF when it's cold out. If the Reductant Heater does not perform as requested, code P20B9 is stored.

    Wiring issue Symptoms

    • DPF regeneration may not occur

    Common Problems That Trigger the P20B9 Code

    • Glow plug control module failure
    • Reductant tank heater failure
    • Wiring issue

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