Home » OBD Code P2209: Fix NOx Heater Sensor Circuit Problem

OBD Code P2209: Fix NOx Heater Sensor Circuit Problem

Code P2209The DTC P2209 is a generic powertrain code that is used to detect the “NOx or the nitric oxide and nitrogen dioxide sensor for the Bank 1 side of the engine.” That denotes that it is solely related to the NOx oxides of nitrogen sensors. These are mainly applied in emission systems that are compatible with diesel engines. Their goal is to detect the optimum levels of NOx emission from the exhaust gasses and the combustion engine. The internal computer might have got some foreign objects from the gaseous mixture rather than the average indicators. The input data of the oxygen sensors and the catalytic converter must exert something familiar in the instance.

In simple words, we can aforementioned that the engine control module (ECM) is capable of detecting the nitrogen oxide (NOx) gasses using particular information from the inlet and outlet of the heavy-heated oxygen sensors in combination with the distinctive NOx sensor readings. This DTC is most probably the engine block suggesting cylinder number one.

Working mechanism: NOx Sensor Heater Sense Circuit Bank 1

Most of you do not know the fact that the NOx Sensor Heater Sense Circuit Bank 1 has been established with two Oxides of Nitrogen (NOx) Sensors. These two Nitrogen (NOx) Sensors have different types of working mechanisms. Those two sensors are, 

  • The upstream NOx Sensor
  • The downstream NOx Sensor

Let us focus on the upstream NOx Sensor first. It is located on the systematic elbow of the Turbocharger, which is connected with the downpipe. This downpipe is vehemently attached to a corresponding NOx Sensor module.

On the contrary, the downstream NOx Sensor is situated on the pervasive outlet of the Selective Catalytic Reduction (SCR) Catalyst. This has a deep relation with the corresponding NOx Sensor Module. This sensor is attached to the right frame rail. It is surmounted to the warm engine block, making sure that the ambiance is quite in favor of the dissection. P2209 Trouble Code

The NOx Sensor Modules can be changed as you like. Those can communicate with the Powertrain Control Module (PCM) in a diversified way. The NOx Sensor Modules must perform the diagnostics compounding that is correlated with the internal diagnostics. The NOx Sensors play a pivotal role in controlling the efficiency of the SCR Catalyst. That’s how these two types of NOx Sensors work harmoniously to make the car untouchable. 

Causes behind the P2209 Trouble Code:

Let us have a look into the causes behind the emanation of the DTC P2209 in maintaining some proper allocations,

  • There may be some sort of failure in the coolant temperature sensor, making it the worst scenario for the car’s emission system. Another most exclusive cause of DTC P2209 may be a defective fuel injection segment.
  • There may be some sort of leakage in the exhaust manifold, Derogatory whipping hose, or in the exhaust system. The downpipe of the NOx Sensor Heater Sense Circuit  Bank 1 may be out of order as it exerts this particular code. 
  • One of the deadliest causes is that the Catalytic converter might be facing the weirdest encounter in the informal procedures. The engine could be misfiring in the shortest possible time. This makes the fuel and combustion situation worse than ever.
  • The Barometric Pressure Sensor could be destroyed by the extreme heat produced by the main engine. Clogged intake and inlet pipe can also harm the NOx Heater Sensor and yield that trouble code.

What are the associated parts of the DTC P2209? 

The associated parts are mostly very much crucial in making the most of the abandonment. In this phase, we will see some of the related parts of the NOx Heater Sensor and also find out their role in perceiving the simplest  form of contribution, 

  • The MAP sensor is perfectly correlated with the NOx Heater Sensor. If this part is defective, it will surely experience the DTC P2209.
  • Mass airflow sensor works almost similar to low compression, and it is responsible for making a harsh demotion in the low fuel pressure. It can also be the cause of expanding this DTC P2209.
  • Fuel injectors are the part that regulates the fuel delivery system, and it also maintains the air-to-fuel ratios in the engine.
  • The O2 sensor, which is the most crucial one in this chart, can damage the entire fuel controlling system, and it is the prime cause of illuminating the error codes.
  • Engine wiring harness and the EGR system are two of the most dominant forces in a system that can change the whole game for the engine.

Common Mistakes When Diagnosing the DTC P2209

DTC P2209 is deeply related to the nitrogen dioxide sensor for Bank 1. The very naïve fault the professional does prefers other parts rather than the nitrogen sensor. The checkings of the fuel pressure regulator and DEF pump could be skipped by any means. They may also not check the Fuel injector perfectly as most of the contaminations are done in this section. These are some of the common fallacies that may be eradicated if the professional maintains the hierarchical order in diagnosing the car.

Codes that are similar to the DTC P2209

Some codes are very much similar to the DTC P2209, and the repairing process is also almost the same as these so that these codes can develop a sense of homogeneity in between the codes. Those codes are,

P2205– “NOx Sensor Heater Control Circuit Open Bank 1”

P2206– “NOx Sensor Heater Control Circuit Low Bank 1”

P2208–  “NOx Sensor Heater Sense Circuit Bank 1”

P2212– “NOx Sensor Heater Sense Circuit Intermittent Bank 1”

P2211– “NOx Sensor Heater Sense Circuit High Bank 1”

Complete diagnosis and repairing process of the DTC P2209

The diagnosis and the repairing process of the DTC P2209 are almost the same as the previous codes. Just a little different is that it is solely related to the NOx Heater Sensor. So it would help if you input more focus into this arena. 

Wirings & Sensor

The first stage is to visually check and monitor the electrical wirings and the sensors of the insides. If you find any faulty sensor or connecter, then replace that without any further delay. Then you must attach the OBD2 code with the car and scan for the error codes. After you find the error code try to solve the codes manually.

Exhaust gasket

Then diagnose the exhaust gasket if there is any sort of leakage in this section; if you find leakages, then repair that. Then diagnose the temperature of the exhaust gasses in the catalytic converter. If the temperature is too excessive, then cool it down. 

O2 Sensor

Diagnose the oxygen sensors, which is very crucial, similar to the NOx Heater Sensor. These sensors work harmoniously so that they can serve the air-fuel mixture ratio of the catalytic converter. Repair and replace the oxygen sensors and change the sensor’s hose if it defects.      


Finally, you need to diagnose the PCM or main computer. If it takes a long time to be in operation, then you must update the software package, and by doing that, it can be resistant to all kinds of bugs and error codes. Thus you can diagnose and repair the DTC P2209 simultaneously. In the end, take a short test drive of the vehicle and ensure that the trouble code is wholly eradicated from the system.


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