Quite often I face different “solutions” with attempts to prevent problems, caused by NOx system.


There are engines, which are manually left in Homogeneous mode, using activation menu; there are engines, which configuration has been altered using NCS or a similar tool. There are engines with modified error message list – the error message 30E9 has been deleted. Needless to say, none of these solutions solves the problems with the vibration of the engine in idle, misfires, the error messages regarding fuel trim, increased CO/HC content in the exhaust (it’s not possible to pass TI). Of course, also the fuel consumption is increased – the engine doesn’t use Stratified charge. The behavior of the engine – quite languid. Cold starts – very incorrect (vibration, shivering).


During this week, I met two exotic cases. They could be even described as curious.

First – the car had all symptoms mentioned above, in addition, the error messages regarding NOx system in the error message memory. Simply saying – a complete set of problems. After purchasing the emulator, the owner of the car tried to register replacement of sensor and catalytic converter, using ISTA D. And here the surprise was waiting for him…


Everything ran smoothly – both identification of car and tests. Till the last menu, in which you have to confirm deleting of specific adaptations.

As you see, there is NO text visible opposite the menu! Choosing any of options, ISTA D informs, that the operation can not be completed. Nor check-up of Ignition status, nor repeated communication of the computer with the car helped.

Also, installation of the newest version of ISTA didn’t help.

My suspicions were confirmed, when I asked the owner of the car to open section of DME Activation. There was no sign of specific parameters of N43/N53. Conclusion – DME configuration has been modified. The curiosity is an obstacle, that all possible error messages regarding NOx problem were recorded in DME error message memory: the effect of all activities was 0.


The second case is even more exotic.

Patient: E90 with N43 series engine.

Problems – incorrect cold starts, vibrating, etc.

Performing quick inspection, I had to conclude: multiple LTFT is around -35 % (a significant difference from 0); the engine works with emergency pressure of HPFP (100 Bar).

Test of HPFP confirmed – also 175 Bar in idle is not a problem – HPFP is performing correctly.

It’s strange, but mechanical efficiency of cylinders No.2and 3 was around +50 .. 80 % against 1-st and 4-th cylinder. ../F5/Shift+F6/F1 live data of injectors indicated around 2 times longer opening period for the injectors of 2-nd and 3-rd cylinders comparing with injectors of cylinders No.1 and No.4 (0.7 ms against around 0.35 ms). How is that possible? DME sees increased mechanical efficiency, but has deliberately increased the opening time of injectors?

Total crash of adaptations?

After deleting adaptations, mechanical efficiency of all cylinders was correct, till heating of wideband probe was initiated. Then DME, without any visible cause, starts to disbalance cylinders. The most interesting is a fact – this engine had only one wideband probe, accordingly such unbalancing of “banks” is illogical.

../F5/F6 although confirmed 2 (!!!) wideband probes are being managed!

NOx sensor didn’t turn on in the necessary moment, although there were no error messages regarding NOx system in the error message memory.

../F5/Shift+F6/F2 confirmed the engine has newer worked in Stratified charge.

../F9/Shift_F3/F1 indicated the sulphation of the NOx sensor is 0 mg, obviously – DME doesn’t even calculate the poisoning! How could that be?


But the most interesting part will only follow. Here, how the DME reacted to the reading of Info error message list:

The Info error message list is not being maintained?


And how about the History list?

Here the situation is even more interesting! Here, a load of error messages, for whom all attributes are “lost”. In addition, all error messages have the same odometer reading (first, one before last, last time of registration). How is that possible? Very simple – incorrectly modified odometer of the car. For now, in attributes of registered error messages smaller milage than the one, recorded by DME, is indicated. And now there is no doubt, that software of DME has been modified. To make a situation even more “fun” – even DME software configuration has been damaged (or an incorrect release has been taken as a base for modifications).

Now the owner of the car has to restore DME software, solve problems of NOx system, re-adaptation of the engine. During several years, no specialist has been able to detect the cause of the problem, and the owner already has ost the hope to finally identify the problem…