What Does the NOx Sensor Do in Your BMW? Problems, Errors, Replacement Costs [ FIX! ]

BMW NOx Sensor – Problems, Errors, Replacement Costs, Prices, FIX / +++

While in this silky smooth and fantastic daily motoring, there are some unfortunate drawbacks as well. The BMW’s NOx sensors operating conditions enable the sensor to measure the nitrogen levels your BMW vehicle normally emits. NOx sensors are responsible for reducing NOx (Diesel Nitrogen Oxide) after-treatment systems, which protect the environment in BMW vehicles with a urea-based SCR mechanism and minimize harmful exhaust gases.

As your BMW’s NOx sensor fails, the ECU cannot detect the number of fuel injectors needed to spray inside the chamber. Due to this reason, the injectors usually begin starving and surging the engine because the ECU cannot examine the optimal amounts. NOx sensors help determine the high levels of NOx and notify the SCR system to adjust itself to accomplish the optimal emissions.

BMW NOx Sensor – Failure Causes

Generally, BMW’s engine comprises two NOx sensors; one is downstream while the other is upstream sensors. The most common causes of failure are ECU water intrusion, soot build-up on the sensor, and cable damage; due to these issues, your engine light will illuminate. For providing good quality and coverage for this significant diesel category, BMW installs diesel NOx sensors.

BMW NOx Sensor Failure Causes Problems Issues
BMW NOx Sensor Failure Causes, Problems, Issues

BMW NOx Sensor Problems

If your BMW’s NOx sensor is not working correctly, you can quickly check out its symptoms and problems, which will help you deal with the issue before your BMW ruins more.

Maximum Fuel Consumption

You may observe increased fuel consumption. As your sensor is not conveying the correct information, engine management software cannot estimate the proper fuel consumption and air-to-fuel ratio. In turn, it will cause the engine’s electronic brain to consider it a worst-case scenario while the fuel mixture reaches its maximum level to acquire maximum power in poor conditions. Dropping in the fuel economy during regular driving is certainly a prominent sign of a faulty sensor.

BMW NOx Sensor Problems Error High Fuel Consumption
BMW NOx Sensor Failure – High Fuel Consumption Issue

Warning Lights

Even though the NOx sensor itself does not actually present in the engine bay, its failure stimulates the engine warning light. Obviously, it does not explicitly show errors in the NOx sensor, but mentions some kind of malfunctioning in your BMW. Since, most probably, you will not visually encounter any problem with the NOx sensor.

Scanning your BMW’s ECU for error codes can help you in locating the error. People having engine code scanners can even find the fault of the NOx sensor at home. Alternatively, your mechanic can also help you in tackling this glitch. One of the drawbacks of reading engine code is that the code may indicate the following issues:

  • Exhaust leak.
  • Oxygen Sensor.
  • Coolant Temperature Sensor.
  • Mass air-flow Sensor.

If you ignore this issue, you may face an AdBlue-System fault in the iDrive screen and on the dashboard.

BMW Check Engine Light BMW NOx Sensor Error
BMW NOx Sensor Problems – BMW Check Engine Light ON

Unstable Idle

One of the most prominent indications of a malfunctioning nitrogen oxide sensor in an N53 and N43 engine is an inadequate engine speed. Typically, fuel engines need to keep a particular fuel flow into the combustion chamber while DME manages the task electronically. Starving and surging of the fuel and faulty sensor can generate an uneven and unstable idle.

BMW NOx Sensor Errors

Go through the following error codes of the BMW NOx sensor with their explanations.

  • 30E0 NOx sensor indicates offset.
  • 30D8 NOx sensor means damaged sensor.
  • 2AF0; 2B05 nitric oxide sensor shows the heating conditions.
  • 30E4 nitric oxide sensor represents aging.
  • AC600 depicts too low SCR System Efficiency.
  • 30D6 nitric oxide sensor represents plausibility.

You can also look over the complete errors and explanations of NOx sensors in BMW.

BMW NOx Sensor Error Codes
BMW NOx Sensor – Error Codes


Durable and exceptional quality, BMW NOx sensors are not cheap; better try to fix the old sensor before replacing the one. Most car owners have successfully dealt with this problem by cleaning and restoring the sensors in proper working conditions. Due to the location of sensors, soot build-up is the main reason for sensor failure. So, with some easy steps, you can try to repair your BMW’s NOx sensors.

BMW NOx Sensor Replacement Guide Tips
BMW NOx Sensor Replacement Guide / Tips
  • First of all, clean the sensor by removing all soot build-up. By doing so, there are high chances that you can bring your sensor back to life.
  • In case cleaning doesn’t work, you have to ask your mechanic for repair.

As NOx is one of your vehicle’s complex components, it is a bit hard to locate the exact point where the issue basically occurs. With advanced and proficient skills, you can fix this problem. Many types of sensors like 4326879 are available in the market, which you can replace.


Depending on the manufacturing and model of BMW, a wide range of sensors with different prices is available. Likewise, you can also check out its replacement cost depending on whether you opt for an aftermarket or factory sensor. Even some market owners have spent four figures in replacing their nitrogen oxide sensors. Research and making comparisons are essential before settling on a particular sensor. If you are cash-strapped, you can also choose refurbished NOx sensors because these sensors are almost two times cheaper compared to the new ones; in this way, you will surely save a considerable amount.

BMW NOx Sensor Prices Replacement Costs
BMW NOx Sensor Prices, Replacement Costs

While the refurbished BMW NOx sensors are more affordable, the issue you may have to face is that they may fail within a few days of replacement. You can prevent yourself from this frustration by ensuring that your sensors must come with a warranty. If you do not have any budget issues, install new sensors. Typically, it will cost around $700 to $900. Even though they may have an eye-watering price tag, but they also have the best warranties. Even if they stop functioning after installation, you can easily claim within the warranty period and effortlessly get a new one.

Undoubtedly, in the modern-day, motoring becomes far more complex and frustrating when issues like NOx sensor failure encounters. Like all other vehicle components, your NOx sensors also have a limited life span, after which you have to replace them. With the help of the given information, you can easily choose the option that will suit you. You can easily opt for refurbished sensors or brand-new BMW NOx sensors, depending on your budget.


This site uses Akismet to reduce spam. Learn how your comment data is processed.