F10/11. Nuances of the NOx catalytic converter

In this entry – about several very interesting nuances, which are typical exactly for MSD87 (N53B30 engine management system, used in F10/11).


BMW engineers have drawn conclusions since the first generation of the N53B30 engines. What are these conclusions?

1. Poisoning of the NOx catalytic converter with the sulfur happens very often (around 90% of vehicles with N53/N43 series engines have the error message 30EA: contamination of the NOx catalytic converter, recorded at least one time till mileage of 100.000km. For more than 50% this error message is recorded regularly). What did BMW do? For the F series, the error message regarding contamination of the NOx catalytic converter is eliminated – the problem was “solved” in such way. Yes, when the catalytic converter is contaminated, MSD87 stops using a Stratified charge, but there are no error messages in the DME error message memory!

2. Desulfation sessions (their priority) are automated. This is a logic correction – why the driver of the car should manually initiate the desulfation session if it could be done automatically? Accordingly – the activation of the desulfation session is eliminated from ISTA D/+.

3. As the typical serving time of the catalytic converter of the NOx system doesn’t reach over 150.000km or very often even 100.00km, the question – how to reduce the number of reclamations – would be logical? Even more – in Germany and other countries, the extended warranty for cars is very popular, and it may apply also to the NOx system. For E series vehicles, the error message 30E9 regarding reduced efficiency of NOx catalytic converter was recorded, but how about F series? The solution is very simple – don’t record the error messages regarding reduced efficiency of the NOx catalytic converters at all or record it in only some rare cases. Yes, formally the error message 180401 is intended, but for many, many F10/F11, which I have diagnosed (even with mileages above 300.000km and 100% of them had obvious problems of the NOx system) I haven’t seen this error message in any error message memory of DME! A perfect solution!

4. As the problems with the NOx catalytic converter are masked deliberately, giving the impression that there are no problems in this system, BMW engineers have done also a logical solution – the registration of the replacement of the NOx catalytic converter is not intended anymore. It sounds as if logical (keeping in mind the way the problems are “solved”) but – there are several nuances, which have to be kept in mind – read further!

5. To the service personnel and enthusiasts to not ask unnecessary questions (what the performance mode mean; when/why the car uses Stratified charge, why the NOx catalytic converter is not cleaned, why the NOx sensor is not sending the data, etc), a perfect solution is found – these data simply are not available! In such a way the BMW has managed to hide all problems with the NOx system pretty well. Perfect!


Desulfation of the NOx catalytic converter

The management of the NOx catalytic converter of the F series is no different in the basic things from Eseries: after each 10 .. 60 seconds the NOx catalytic converter is regenerated for several seconds – cleaned from accumulated nitrite, after each (max) 1000 .. 4000km (depending of the performance of the NOx catalytic converter) – desulfated. Basic info read here.

Desulfation happens when driving for a long while with a speed of 110+km/h. Unfortunately, the owner of the car has no information available that the NOx catalytic converter is critically contaminated (as mentioned before, the dealer has no information regarding contamination of the catalytic converter), that the desulfation session would be performed successfully, etc.

The only solution: INPA. INPA has the NOx catalytic converter menu available: ../F6/F2/F5

Here, in the menu, you see the contamination of the NOx catalytic converter (marked with red). Typical values, by which typically the critical contamination of the NOx catalytic converter is in effect (and the engine stops using Stratified charge):

a) around 1500 .. 2000mg for a new NOx catalytic converter;

b) around 500 .. 700mg for used (100.000+km) NOx catalytic converter;

c) around 3000 .. 3500mg for NOXEM emulator.

Accordingly, the desulfation session has to be performed at least once for each 100 .. 1200km for a used catalytic converter or 6000 .. 7000km in case of NOXEM installation.

As the possibility to register replacement of the NOx catalytic converter, the question – how to “clean” the data of the contamination of the NOx catalytic converter if NOXEM is used, but there is no possibility to perform a desulfation session – topical.

Note: problems the perform real desulfation sessions for many N43/N53 series engine owners are due to speed limitations (in many countries the fines for speeding for +20km/h and more are very high), due to heavy traffic on the main roads, unavailability of long roads.

Unfortunately, ISTA D/+ does not delete the contamination data of the NOx catalytic converter, if the adaptations of the engine are deleted.

The only solution: INPA. Here,the menu after deleting the adaptations (../F6/F3/F2/F6):

As we see, the contamination of the NOx catalytic converter is omg, the catalytic converter is ready for next 6000+km (of course, if the NOXEM is installed).

Unfortunately, if INPA is not available, there is no other way to clean the NOx catalytic converter – the real desulfation session has to be performed!

If your car has NOXEM installed, you can use the error message 12C401 to identify the problems (most typical: contamination of the NOx catalytic converter). This is the only way how to obtain the information that the engine of your car works in the emergency mode and does not use a Stratified charge. More about it read here.