P2206 Low level of the control circuit of the NOx sensor heater, bank 1

P2206 Low level of the control circuit of the NOx sensor heater, bank 1

OBD-II DTC Datasheet

NOx Sensor Heater Control Circuit Bank 1 Low

What does this mean?

This is a generic powertrain diagnostic trouble code (DTC) and is commonly applied to OBD-II vehicles. Car brands may include, but are not limited to, BMW, Dodge, Ram, Audi, Cummins, etc.

NOx (nitrogen oxide) sensors are mainly used for emission systems in diesel engines. Their primary use is to determine the levels of NOx escaping from exhaust gases after combustion in a combustion chamber. The system then processes them using different methods. Given the harsh operating conditions of these sensors, they are made up of a combination of ceramic and a specific type of zirconia.

One of the disadvantages of NOx emissions to the atmosphere is that they can sometimes cause smog and / or acid rain. Failure to monitor and regulate NOx levels will have a significant impact on the atmosphere around us and the air we breathe. The ECM (Engine Control Module) constantly monitors the NOx sensors to ensure acceptable levels of emissions in your vehicle's exhaust gases. The NOx sensor heater control circuit is responsible for preheating the sensor. This is to speed up the sensor warming up, which in turn effectively brings it to operating temperature without relying solely on the exhaust gas temperature for self-heating.

When it comes to P2206 and related codes, the NOx sensor heater control circuit is faulty somehow and the ECM has detected it. For reference, bank 1 is on the side that cylinder number 1 is on. Bank 2 is on the other side. If your vehicle is a straight 6 or 4 cylinder single head engine, it could be a two way gutter / manifold. Always refer to your service manual for location designations, as this will be an integral part of the diagnostic process.

P2206 is a generic DTC that relates to NOx Sensor Heater Control Circuit Low Bank 1. It occurs when the ECM detects a lower-than-expected voltage on the bank 1 NOx sensor heater control circuit.

Diesel engines especially generate significant amounts of heat, so be sure to let the system cool down before working on any exhaust system components.

Example of a NOx sensor (in this case for GM vehicles):

What is the severity of this DTC?

Medium severity as emissions related faults can indeed affect the environment. However, sometimes there will be no symptoms for outlier faults, but they can still have consequences if left unattended.

What are some of the symptoms of the code?

Symptoms of a P2206 diagnostic code may include:

• Failed emission test
• Intermittent CEL (check engine light)

What are some of the common causes for the code?

Reasons for this P2206 cruise control code may include:

• NOx sensor defective
• Defective heater in NOx sensor
• Internal open circuit in the ECM (engine control module) or in the NOx sensor itself
• Water invasion
• Broken connector tabs (intermittent connection)
• Fused harness
• Dirty touch element
• High resistance in heater control circuit

What are some of the steps to troubleshoot a P2206?

The first step in the process of troubleshooting any problem is to review technical service bulletins (TSBs) for known problems with a particular vehicle.

Advanced diagnostic steps become very vehicle specific and may require appropriate advanced equipment and knowledge to be performed accurately. We outline the basic steps below, but refer to your vehicle / make / model / transmission repair manual for specific steps for your vehicle.

Basic step # 1

Most NOx sensors used in diesel cars and trucks will be reasonably available. Given this fact, keep in mind that they can be extremely stubborn when pulling off with all the expansions and contractions that occur due to temperature fluctuations in the exhaust system. Therefore, before doing this, make sure you need to remove the sensor. Most sensor testing can be done through the connector. Refer to your service manual for accurate NOx sensor tests to get the desired values.

NOTE. You may need to warm up a bit when replacing the NOx sensor to avoid damaging the threads in the exhaust plug. Penetrant oil is always a good idea if you think you'll be removing the sensor in the near future.

Basic step # 2

Keep an eye on the seatbelt of the NOx sensor to assess its performance. In most cases, the suspensions will operate in close proximity to the temperature extremes previously mentioned. Therefore, keep a close eye on melted looms or connectors. Be sure to repair any scuffs or damaged looms to prevent any future malfunctions.

Basic step # 3

Inspect the exhaust system. Especially inside, to determine if there is enough soot, which could potentially adversely affect the overall functionality of the sensor. Generally speaking, diesel engines already emitted an abnormal amount of soot. That being said, aftermarket programmer updates can affect the fuel mixture and create more soot than normal, which as a consequence can cause premature NOx sensor failure given the richer fuel mixtures associated with some aftermarket programmers. Be sure to clean the sensor if you believe it to be and return the fuel mixture to normal OEM specifications by removing or disabling the programmer.

Basic step # 4

Finally, if you have exhausted your resources and still cannot identify the problem, it would be a good idea to find your ECM (Engine Control Module) to check if water intrusion is present. It is sometimes found in the passenger compartment of a car and can be susceptible to any moisture that forms in the passenger compartment over time (eg heater core leaks, window seals leaking, residual snow melting, etc.). If any significant damage is found, it will need to be replaced. For this, in most cases, the new engine control unit must be reprogrammed for the vehicle in order for the adaptation to be problem-free. Unfortunately, generally speaking, dealerships will be the only ones with the right programming tools.

This article is for informational purposes only and technical data and service bulletins for your specific vehicle should always take priority.

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