Q1: Why my car needs NOx sensor?
A1: NOx sensor monitors NOx amount in exhaust gases. Without these data, engine disables Stratified charge and Homogeneous lean injection modes. As the result, fuel consumption grows. Also, there are some side effects if NOx sensor is broken or disconnected (also, if error messages relating NOx catalytic converter are recorded): engine starts shaking; rough run and misfires appear. Problems with NOx system can be the cause of error messages about fuel trim, Lambda probes, insufficient efficiency of CO converters, misfires. More information read here.

Q2: What is the difference between NOXEM NOx emulator and OEM NOx sensor?

A2: The OEM NOx sensor measures a series of exhaust gas parameters, including the content of NOx in them. If the NOx catalytic converter has aged or is damaged, the NOx sensor determines it – the need to replace the expensive catalytic converter is inevitable. The NOXEM NOx emulator “informs” system, that the level of NOx in exhaust is acceptable, regardless of technical condition of NOx catalytic converter, and there is no need to change NOx the catalytic converter anymore. NOXEM allows you to save more than EUR 2000.

Q3: What are the main differences between NOXEM emulator and ‘’usual’’ emulators?

A3: NOXEM des not ‘’cheats’’ all signals necessary for measurements. NOXEM measures all possible parameters in real time. Also NOXEM does not use ‘’record/playback’’ principle, but generates output parameters based on deep understanding and mathematical model of NOx system. This manner guarantees best possible performance over all conditions.

Q4: Is NOXEM safe for my car?

A4: Yes, NOXEM is absolutely safe for your car. NOXEM installation is ‘’plug and play’’ and do not require any wire cutting and/or specific connection to your cars electronics. We have explored genuine data transmit protocol, and NOXEM responds the same as OEM made NOx sensor. From engine’s ‘’side’’ there is no difference between NOx sensor and NOXEM NOx emulator.

Q5: Will emissions rise significantly if I will install NOXEM instead OEM NOx sensor?

A5: Situation is little bit complicated than it look’s at the first moment.
At idle, N43/N53 engine can work in both Homogeneous mode and in Stratified charge mode as well. In Homogeneous mode NOx content is close to 0 (and is reduced by CO converters), and there is no difference between NOXEM and OEM sensor. If Stratified charge is selected at idle, NOx amount is small (because amount of burned fuel also is very small). At idle MSD80 does not makes any decisions based on NOx content (i.e.: does not controls efficiency of NOx catalytic converter) – there is no difference between NOXEM and OEM NOx sensor.
At loads more than 60% (corresponding driving speed: from 120 .. 160km/h, depending on engine) engine switches to Homogeneous mode and emitted NOx content is close to 0. In homogeneous mode NOx content is reduced by using CO converters, not NOx converter. And again – there is no difference between NOXEM and OEM NOx sensor.
At low loads NOx content corresponds to EURO4/5, if remaining efficiency of NOx converter is around at least 10 .. 20% because of small amount of burned fuel and high efficiency of engine.
The worst region (from emission side) is driving with speed 70..120..160km/h, while engine performs Stratified charge. In this area NOx content could exceed allowed limits if remaining efficiency of NOx converter is low. In the same time – content of CO and CH is significantly lower comparing with same engine, working on Homogeneous mode (if there are problems with NOx system).
Moreover – almost all of N43/N53 series engines with NOx system problems (error messages related to NOx converter and/or NOx sensor) are working with serious unevenness – as the result of un-optimal fuel/air ratio, and produce very high levels of CO and CH. Installing of NOXEM solve problems with long term fuel mixture adaptation creation, restores correct fuel mixture and reduce CO and CH content while engine performs Homogeneous mode.

Q6: Will I pass the technical inspection, if the NOXEM 129 or NOXEM 130 is installed on my vehicle?

A6: Yes, you will pass the technical inspection if all systems (except NOx catalytic converter) are in working condition – NOXEM will not affect it in any negative way. On the contrary – if the NOXEM is in use, the engine will perform in Stratified charge mode, which significantly reduces values of CO and HC (and reduces load to CO catalytic converters), measured in exhaust gases.

Q7: Is it possible to identify (during any type of technical inspection), that the NOx catalytic converter is damaged, and the NOXEM is installed?

A7: No, it is not possible to identify it. The engine produces higher level of NOx only under real load conditions. While the exhaust gases are measured, the vehicle stands still (independently of the range of RPM), and the level of NOx will be in accordance with admissible standards. Both visual inspection of vehicle’s exhaust system and testing with specialized diagnostic equipment will not show any suspicious differences, that the control systems of the vehicle have been modified. Moreover – regular technical inspections does not include measurements of NOx amount in exhaust gases.

Q8: If I use NOXEM, will I have fuel economy?

A8: Yes, the use of NOXEM will decrease fuel consumption for at least 15 .. 25%, comparing to vehicle, which has problems with NOx catalytic converter and/or NOx sensor, and at least 5 .. 10% comparing to vehicle, which NOx catalytic converter has good performance and there are no technical problems with NOx system components. NOXEM requires regeneration of NOx catalytic converter max rare (each 50 .. 60 seconds) and desulphation – with max low exhaust system temperature. Both conditions guarantee max low fuel consumption and max long work life of exhaust system.

How does NOXEM allow you to save fuel?
NOXEM allows you save extra 5..10% (usually around 10%) of fuel, comparing to OEM NOx sensor. How? NOXEM initializes regeneration of NOx catalytic converter max rare – average after 50 .. 55 seconds. In case of OEM NOx sensor, NOx catalytic converter is regenerated after 10 .. 20 seconds. During regeneration, the engine burns the additional amount of fuel to heat the NOx catalytic converter. The less often the regeneration, the less fuel “waste”. Also desulphation sessions NOXEM initializes max rare – 3 .. 5 times less than OEM NOx sensor. In the process of desulphation also an additional amount of fuel is burned, to keep the temperature of exhaust system high. Moreover, when using NOXEM, you can avoid desulphation sessions at all – it allows you to save both, additional fuel and money.

Q9: If I will not like the performance of NOXEM – will I be able to go back to original setup of exhaust system?

A9: Yes, you will be able to go back to original setup of exhaust system. If you will use your right of withdrawal, Bimmerprofs will return the money you spent on NOXEM (read more in warranty terms). The NOXEM does not interfere with structure of exhaust system or management system structure, so anytime you want, you can go back to original setup.

Q10: Which product – NOXEM 129 or NOXEM 130 – should I choose?

A10: We suggest to use realoem.com to specify the code of NOx sensor by your vehicle’s VIN code. If you know the vehicle body code and series of the engine – check the description of NOXEM products.

Q11: Are any additional procedures required after installation of NOXEM?

A11: Yes, after installation of NOXEM, you have to perform the encoding of new NOx sensor and new NOx catalytic converter, as described in instruction of product. If these service procedures will be ignored, NOXEM will not perform as it’s supposed to – the engine control unit will consider, that the NOx catalytic converter is still damaged and has to be replaced.

Required equipment: OBD to USB cable and ISTA D software.

Detailed description read here.

Q12: Does the use of NOXEM differs from exploitation of original exhaust system, installed by manufacturer?

A12: No, the exploitation of NOXEM does not differ from exploitation of NOx sensor, supplied by manufacturer. The engine will perform all intended functions as with original NOx sensor, including regeneration and desulphation of NOx catalytic converter.

Q13: What is the resource of NOXEM?

A13: NOXEM uses only original Bosch sensors (newest generation), the work life of which exceeds 300’000 km. And you will not have to worry about resource of NOx catalytic converter anymore. Additionally, Bimmerprofs offers lifetime warranty to electronics part of product (read more in warranty terms).

Q14: The error message memory of my car’s engine control unit shows the error message 30EA, and the specialist (in BMW service) says that the NOx catalytic converter requires desulphation. I live in densely populated area, and have no appropriate roads in near reach to perform the process (it’s necessary to drive with speed 110 km/h for at least 30 minutes). And also the desuplhuring process requires some special activation, control of process, where special diagnostic’s tools are necessary. Will NOXEM solve my problem?

A14: Yes, NOXEM will solve your problem. Only after each 7’000 .. 8’000 km (up to 15’000 km with latest software releases of MSD80) you will have to spend some 5 minutes, and delete the information regarding sulphuring of NOx catalytic converter, using INPA, ISTA D or similar software. There will be no need to look for specific road section, no risking with penalties for speeding, no control of desulphuring process – no money & time expenses.

How to encode new NOx catalytic converter, read here.

Q15: After old adaptations are cleared, some new error messages appeared. Something went wrong?

A15: This is a normal situation. When adaptations are cleared, following error messages* can appear immediately:

  • error messages relating DSC. Solution: drive 10 .. 15 min, switch off ignition for 2 .. 3 min, then turn on;
  • error messages relating throttle. Solution: turn on ignition, press and release accelerator pedal for 3 times, then start engine.

During adaptation process (after old adaptations have been cleared) some error messages* can appear:

  • error messages relating fuel trim (bank and/or cylinders individually);
  • insufficient performance of CO catalytic converters;
  • Lambda probes (trim and/or signal);
  • uneven run (Stratified charge and/or Homogeneous injection).

*these error messages in the exact situation do not indicate any problems with the engine performance.

After new adaptations are completed (after 5 .. 8 driving sessions for cold/warm engine, at least 200 .. 300 km), check the new adaptations and clear error message memory using INPA or ISTA D, if necessary.

How to perform adaptations read here and here.

Q16: Can I demount NOx catalytic converter after installing the NOXEM?

A16: Yes, you can demount the NOx catalytic converter, replace it with a silencer or install custom exhaust.

Q17: Should the CO catalytic converters be in working order for N43/N53 to perform in full?

A17: Yes, the CO catalytic converters should be in technical order. If the engine management unit will diagnose them as not fit, it will record an error message regarding CO catalytic converters and it wil not allow the Stratified charge, and all benefits of engines mentioned before will not be available.

Q18: The price for used NOx sensor is significantly lower. Is it worth to buy it?

A18: The NOx sensor is very sensitive and fragile tool. Much more fragile and sensitive to any type of overloads, for example, of Lambda probes. Increased temperature, increased oil product content in exhaust gases, water condensation are having huge impact on NOx sensor and damages it. Average work life of NOx sensor is only around 50’000 km. We categorically don’t recommend to purchase used NOx sensor – it won’t be even a short-term solution.

Q19: If I choose to replace the NOx sensor to OEM NOx sensor, is it important to purchase the NOx sensor exactly from BMW AG/BMW dealer?

A19: Although all NOx sensors look’s the same (Continental produces them according to directions from NGK), each model has it’s own, separate data exchange protocol. MSD80 will not understand inappropriate data from sensor. Also each NOx sensor contains ID information. If MSD80 will receive data regarding inappropriate NOx sensor (for example, intended to other car model, fuel type or software release), it will not even turn this sensor Online – won’t even try to read data sent by the sensor.

Q20: My car has problems with NOx system. In addition, error message’s list contains error messages relating 5th cylinder (misfires), also error message relating efficiency of CO catalytic converter is recorded. Should I replace injectors, ignition coils, spark plugs first?

A20: In case, if there are problems with NOx system, MSD80 create totally incorrect cylinder’s individual LTFT and usually following error messages appear:

29D1: misfires of 5th cylinder;

29F5: efficiency of CO converter below threshold, bank 2.

Also error messages regarding fuel trim (especially, for bank 2) usually appears. Problems with NOx system also can be the reason of: error messages relating (individual or all) cylinder’s misfires; low efficiency of CO catalytic converter, 1st Bank; Lambda probes; incorrect fuel trim (cylinder’s individual or Bank).

Problems with NOx system (NOx sensor and/or NOx catalytic converter) can be the reason of following error messages:

29CC misfirings, several cylinders

29CD misfirings, cylinder 1

29CE misfirings, cylinder 2

29CF misfirings, cylinder 3

29D0 misfirings, cylinder 4

29D1 misfirings, cylinder 5

29D2 misfirings, cylinder 6

29E0 fuel mixture control

29E1 fuel mixture control 2

29F4 catalytic converter conversion

29F5 catalytic converter conversion 2

2A2B fuel mixture control

2A2C fuel mixture control 2

2C31 Lambda probe in front of catalytic converter, trimming control

2C32 Lambda probe in front of catalytic converter 2, trimming control

2C7E Lambda probe behind catalytic converter, trimming control

2C7F Lambda probe behind catalytic converter 2, trimming control


None of these messages (in exact situation – when/if NOx system is damaged) usually has a real cause, all of them usually are the result of incorrect operation of MSD80. Detailed information read here.

Q21: How significant is to keep the NOx catalytic converter clean of nitrites and sulfur? Could the clogged NOx catalytic converter impair the engine performance (torque)?

A21: The amount on nitrites, accumulated in NOx catalytic converter, is measured in milligrams, but the amount of sulfur – in several grams. Critical boundary, when MSD80 considers that NOx catalytic converter is critically polluted with sulfur, is 3 .. 4 grams, which can not decrease the power of the engine in any way (the layer of sulfur on the walls of catalytic converter can be measured in microns). Even in cases, when due to damaged crankcase ventilation membrane, the engine had huge oil consumption, and the NOx catalytic converter was removed because of suspicion, that is has been clogged because of burned oil, the suspicion didn’t proved correct. No improvements of torque were observed after disassembling the NOx catalytic converter.

Q22: I installed NOXEM on my car. After a long while (I’ve traveled more than 4000 km), the poisoning (with sulfur) parameter of NOx catalytic converter has reached more than 2000 mg. Why it’s like that? Shouldn’t this parameter be with a lower value?

A22: MSD calculates the level of sulfur poisoning, using the mathematical method – it increases proportionally to the fuel amount, burned in the engine. If MSD detects, that the NOx catalytic has perfect performance abilities (NOXEM gives exactly this information), MSD allows the very high level of poisoning (even 3000+ mg), desulphation sessions are required max rare. Using NOXEM, intervals between desulphation sessions can reach even 6000 .. 8000 km (and “cleaning” of NOx catalytic converter will be relatively quick), in the same time OEM systems (OEM NOx sensor and NOx catalytic converter with average performance) will require desulphation sessions even after 1000 .. 1500 km (when poisoning parameter reaches 500 .. 800 mg), and these sessions are relatively longer (NOx catalytic converter is “cleaning” much slower). Accordingly – using NOXEM – the sulfur poisoning parameter can reach much higher level than in case of OEM NOx sensor, and that is normal – nothing to worry about.