F10/11. Problems of the NOx sensor

In this entry, I will try to compile the information, which you need to know about the NOx sensors, installed on N53B30 engines of the F series.


Code of the NOx sensor:11787590402

As you would notice, the “heads” of the NOx sensors are manufactured by NGK (the only manufacturer in the world, who manufactures the “heads” of the NOx sensors), sensors itself are manufactured by Continental. Hardware is identical for all modern NOx sensors. Two things are different:

  • the length of the cable from the “head” to the controller. For this sensor, it’s the longest one between sensors, intended for the BMW petrol engines;
  • type of communication with DME. These sensors are communicating significantly different than the “old” NOx sensors, which were intended for the N43/N53 series engines of E series.

Due to both reasons mentioned before, it is not even worth to connect any other, as if “similar” sensor. DME will ignore the data, sent by it.

Even more, for MSD87 the ID control of NOx system is introduced and also a specific error message – 12CE01 Nitrogen-oxide sensor version: incorrect – is introduced.

It goes without saying, that it makes no sense to install the “analogs”, purchased from China or used sensors – it’s a complete waste of money.


As for others (also/even the newest releases) NOx sensors, these ones have a very common hidden defect with its self-calibration of the cells.


Short description of the problem.

The NOx sensor consists of two, sequentially connected electro-chemical cells. In the first cell, the oxygen, “caught up” in the probe, is measured, in the second – the amount of nitrites is measured. For the electronics of the sensor to be able to work correctly, both cells have to be balanced in “zero” or the reference level. Unfortunately, if the cells are started to clog (it can happen if the soot or any other products of low-quality fuel, high amount of the sulfur get inside the probe), the sensor is not able to proceed with this procedure. It tries to do it for a long time, sends the message to the DME: “wait a little bit more, I will be ready just now”. Unfortunately this “just now” arrives late (we talk about minutes, sometimes – hours), sometimes – never appear.

In connection with this problem, three aspects will have to be taken into account:

  • in case of this problem, DME, when reaching a certain temperature of the engine, will turn on the Stratified charge for a short time (several minutes), but then – turn off till the moment, while the sensor will solve its problems. If the sensor does not solve the problems and doesn’t start to send the data, Stratified charge stays turned off;
  • turned off Stratified charge means increased consumption of fuel, problems with vibration when driving, clumsy engine and behavior of the gearbox. Reason for all problems – a range of specific measurements, which are possible during Stratified charge only, is not performed. If there are no these measurements, there are no correct adaptations of the injectors;
  • no error messages are recorded in the DME error message memory, which makes identification of this problem much more complicated.

The situation is made even more complicated with a fact, that not INPA, nor ISTA D/+ shows live data of the NOx sensor. Obviously, BMW believes that this information is too complicated for the “simple” diagnostics specialist, or – simply tries to hide the problem, mentioned before (the fact, that sensor actually does not sends any data – it could be a reason of the huge amount of reclamations and expenses).

If you plan to purchase or use an F series car with an engine of N53B30 series family, perform the test of Stratified charge as described here. It is the only way how to make sure, that the car works as intended (or get a confirmation, that the engine has problems, despite the empty error message list).

Unfortunately, like the other NOx sensors, also this (because the hardware is identical) serves for a relatively short time. The optimistic prognosis: 30 .. 50.000km. Relatively often the error messages regarding complete damage appear already after 10 .. 20.000km, but the problem of (not)sending the data – even earlier.

Leaking injectors: fuel explosions in the exhaust, high oil consumption, condensate in the exhaust – these problems damage the NOx sensor immediately.