P20AA OBD-II: Reductant Injection Air Pressure Control Valve Stuck Open
P20AA Severity
Should you fix P20AA yourself?
Identifying an OBD code is just the start of a complete diagnostic routine. Most trouble codes are caused by a sensor reporting a value that is out of range. Just replacing a sensor may not fix underlying issues. Be sure to understand the code, the part or system in your car that the code refers to, and the risks of delaying professional repair.
Proper diagnosis will save you time and money on unnecessary repairs.
Urgent codes indicate immediate action is necessary. These are urgent and significant malfunctions that can cause severe damage to the vehicle or harm the driver and passengers.
What causes OBD-II fault code P20AA?
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 Pressure Control Valve allows excess air to be vented outside the Diesel Particulate Filter (DPF) System. If the valve fails to operate as requested, code P20AA is stored.
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