What is the P20B9 fault number? What is the description of the Reduction Heater “A” Control Circuit / Open fault? How do I fix the P20B9 fault code What are the symptoms and causes for the P20B9 fault code
What is the P20B9 Fault code? What does it mean
Fault code P20B9 is a sign “Reductive Heater “A” Control Circuit/Open” . This code is set when the heater’s reductant is not operating as it should. This code is triggered when the powertrain control module, or PCM, cannot receive voltage from the “A” heater control circuit. Circuit “A” is valid for vehicles that have more than one reductant heater. To determine which circuit “A”, consult the manual.
While the catalyst system is responsible for reducing all exhaust gases, some applications may also be equipped with a NOxtrap. EGR systems, which reduce NOx by exhaust gas recirculation (EGR), go one step further. Today’s diesel engines are larger and more powerful, but they cannot meet the emission standards. SCR systems are selective catalytic reductions (SCR) systems.
SCR systems inject either a reducing agent or a diesel exhaust liquid (DEF/Adblue) into the exhaust pipe before the diesel particulate filter/catalytic converter. The liquid is injected precisely and reduces the temperature of filtration elements, making them more efficient. The harmful Nitric Oxides are (NOx) reduced into water and nitrogen, and released into the air as steam.
The monitoring of the entire selective catalytic reduce system is done by the PCM (or a dedicated SCR controller module). SCR control module. It regulates the injection timing for diesel exhaust fluid, by checking the data from the NOx sensor, oxygen sensor, and exhaust gas temperature sensor.
A heater is used in this system to prevent diesel exhaust fluid crystallization and freezing. The heater is located either in the diesel exhaust fluid filter compartment or the reductant injection feed hose. This code is set by the PCM if it does not receive any voltage signal from a reductant “A” heater control circuit.
The P20B9 fault code can affect vehicles of all makes and models, including but not limited to Ford, Mercedes, Duramax Jaguar, Duramax Jaguar, Volkswagen, Mazda Mazda, Dodge, Dacia and Audi.
What Causes the P20B9 Fault code?
These are the most common reasons that P20B9 triggers fault code
- – Shorts or opens in the circuit controlling the heater reductant “A”.
- – Defective reductant temperature sensor
- – Defective reducer heater
- – Broken cables or loose, corroded connections
- – Programming error or defective SCR module/PCM
What are the symptoms of the P20B9 fault code?
You may experience the following symptoms if your vehicle has the code P20B9.
- – Illumination and control of the check engine light
- – Lower engine performance
- – Increased fuel consumption
- – Excessive black smoke coming from the exhaust
- – Diesel particulate filter (DPF) regeneration may not occur
- – Other fault codes for the SCR system
How to Fix the P20B9 Fault Code
The following repairs can help resolve the P20B9 fault codes:
- – Replacing the “A” heater control circuit that is defective by the reductant
- – Repair of damaged or missing cables and connectors
- Troubleshooting an open or short circuit in your wiring harness
- – Removing old exhaust fluid
- – Replacing faulty reduction heater
- – Removing the defective sensor for the reductant heater
- – Reprogramming or replacement of the defective SCR module/PCM
How serious is the P20B9 Fault code?
P20B9 should be taken seriously and addressed as soon as possible. It is possible to disable the SCR system. Catalyst damage can occur if the conditions contributing to code retention aren’t corrected in a timely fashion.
