Technical Description of OBD-II Trouble Code
Low Circuit in Bank 1 NOx Sensor
What does that signify?
This is a generic diagnostic trouble code (DTC) for the powertrain and is commonly found in OBD-II vehicles. This can apply to various vehicle brands such as Ford, Mercedes Benz, BMW, VW, Audi, Chevrolet, GMC, Dodge, Ram, Sprinter, and others. While it is a generic code, the specific repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
In general, diesel-fueled engines produce higher levels of particulate matter (PM) and Nitrogen Oxide (NOx) emissions compared to gasoline engines.
As vehicle technology advances, so do the emission standards set by state and provincial laws. Engineers are constantly developing methods to reduce atmospheric emissions in vehicles to meet and exceed these emission requirements.
The Engine Control Module (ECM) continuously monitors numerous sensors to ensure the engine’s efficiency, reliability, and functionality. It also actively monitors emissions to minimize the release of hydrocarbons into the atmosphere. The NOx sensor is used by the ECM to measure nitrogen oxide levels in the exhaust, providing information about the hydrocarbons being emitted. NOx is a primary particulate matter produced by diesel engines. The ECM monitors this sensor and adjusts the system accordingly.
It is important to note that the exhaust of a diesel engine is a highly contaminated area. Soot from the exhaust can accumulate on sensors and switches, potentially affecting their performance. This becomes significant because if the sensor is obstructed, it may not accurately measure the values required by the ECM to adjust the EVAP (Evaporative Emissions) system according to specific federal, state, or provincial laws. In some cases, aftermarket sensors are used to comply with local emission standards when traveling between states with different regulations.
The ECM triggers the P2202 code and related codes (P2200, P2201, P2203, and P2204) when it detects a fault in the NOx sensors or their circuits. Based on my limited experience with this code, it is likely to be a mechanical issue, considering the conditions mentioned earlier.
The P2202 code is set when the ECM detects a low voltage condition in the bank #1 NOx sensor or circuit.
Note: In engines with multiple banks of cylinders (e.g., V6, V8), bank 1 refers to the side of the engine that contains the #1 cylinder. Therefore, the NOx sensor is located in the exhaust of that bank. Refer to your service manual for specific details about your vehicle’s make, model, and powertrain. The service manual is the primary resource for identifying the specific sensor among the many possibilities. Similar distinctions are made for O2 (oxygen) sensors.
Here is an example of a NOx sensor for GM vehicles:
What is the severity of this DTC?
In most cases, emission-related codes are relatively low on the severity scale, especially when compared to potential hazards in other vehicle systems such as steering, suspension, and brakes. If you have more pressing issues to address, you can prioritize those over this code. However, it is important to address any electrical faults with a sense of urgency.
What are some of the symptoms of the code?
Some symptoms of a P2202 trouble code may include:
What are some of the common causes of the code?
The causes of this P2202 fuel trim code may include:
What are some P2202 troubleshooting steps?
Start by visually inspecting the sensor and its harness. Sometimes, external elements can cause faults in our vehicles. I have seen sensors like these damaged by rocks, curbs, snow, and ice. Ensure that the sensor is intact and in good condition. Keep in mind that some harnesses may be located close to the exhaust, so there is a possibility of wires getting burnt or melted, leading to various problems.
TIP: Allow the engine to cool before working near the exhaust.
Clean the sensor. Remember that any sensor mounted in the exhaust undergoes numerous heating and cooling cycles. As a result, they may become stuck in the sensor “bung” (thread hole) on the exhaust. If this happens, you may need to apply heat to the threads, but avoid direct heat on the sensor itself to prevent damage. If you are not experienced in using heat to loosen nuts or bolts, it is best to avoid attempting it. If you have any doubts about your skills or abilities, it is always advisable to take your vehicle to a reputable service station.
