P20C5 - OBD II Trouble Code

January 31, 2017

Our automotive experts have put together the following information about the P20C5 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P20C5 code.

OBD II Fault Code

  • OBD II P20C5

OBD-II Code Wiring issue is defined as a Reductant Heater "D" 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 P20C5 is stored.

Wiring issue Symptoms

  • DPF regeneration may not occur

Common Problems That Trigger the P20C5 Code

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

About the Author

Brad Kava is an automotive expert at RepairPal, the leading online source of auto repair resources and estimates. With many ASE Master certified mechanics on staff who have decades of experience, RepairPal knows all the fine points of car repair.

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