This time – a typical example of how the User Vulgaris succeeds with the repairs of N53 series engines. The situation is not encouraging, and the manufacturer BMW AG is largely to blame. 

In this example: E series vehicle, N53 series engine with endless problems. Increased fuel consumption, vibration of the engine, misfires, and switched-off cylinders. I got the diagnostics data and had to conclude that the only error messages were regarding turned-off cylinders: 

Why so? The answer is simple – as cylinders were turned off regularly, the owner of the vehicle used the only “solution” known to him: deleting the error messages. Immediately after such “repair”, DME re-enables all cylinders, and it is possible to use the car for some time till the next EML (Check engine) in KOMBI. Saving freeze-frame of other error messages – unfortunately, this is not the common practice. 

The reason for increased fuel consumption could be a switched-off Stratified charge. In turn, the Stratified charge is switched off due to some problems with the elements of this system: the catalytic converter and/or the sensor. Due to these problems – a vibrating engine and misfires are not surprising. Even if the engine has other issues, the basic things (including the NOx system) must be brought in order first. Only when the Stratified charge is restored, the engine renew adaptations of banks and cylinder’s individual.  

A good thing is that BMW has leaked INPA, developed by themselves. Only this software has two other error message lists – Info and History, available. True, though, it should be added that this tool is not allowed to be used by the specialists of the dealer centers! 

The history list did not have many surprises, but in addition to turned-off cylinders: 

the error message 30EA appears in the list. This error message indicates a contaminated NOx catalytic converter.

But in the Info list, there are some more interesting things:

It turns out that, exactly here, the 30EA error message hides! Why this error message can not be seen in the Main list? The reason is simple: this error message has been deleted regularly! Like some other specific error messages (for example, 2FCA, 2FDA, and others), after deleting, this error message “hides” in the Info list. In addition, as we can see, its status is still active (vorhanden)! Here, this is the first reason why the Stratified charge is turned off. I, in turn, have a first question for BMW AG: why does such an important error message (which has a fundamental impact on the performance of DME and engine), with active status, “disappear” from the Main error message list? 

And without further delay, also the following objections to BMW AG: how so? Info and History list are not even available in ISTA! How the repair technicians (even the employees of the dealer centers) are supposed to know that the desulfation session should be performed? The answer is simple: they can’t! 

Next nuance: in the attributes of the error message, we see that the contamination of the catalytic converter is 450 mg. Obviously, with such a level of contamination, the performance of the catalytic converter has dropped so severely that immediate purification is required. Is 450mg a lot? Or little? How fast does the catalytic converter get contaminated? From the manufacturer: zero information. The truth is quite sad: 450 mg means some 15 .. 20 % of the performance of a new catalytic converter. So poor performance of the catalytic converter means long and painful desulfation sessions every 500 .. 800 km or even often. If these are not performed promptly, the Stratified charge is turned off immediately.

Turned-off Stratified charge means increased fuel consumption. But, what is even more important – without Stratified charge, a range of specific injector measurements and tests are impossible. Without updated injector data, the fuel mixture in cylinders soon becomes incorrect; the engine vibrates, and misfires appear. And, what is even more harsh – the CO catalytic converters are getting damaged. The price of new CO catalytic converters currently reaches EUR 4000 (if you return the old/damaged converters to the manufacturer) or more than EUR 7000 if you want an “unconditional” purchase. And again – there are no messages regarding the turned-off Stratified charge, neither in KOMBI nor on the screen of the navigation system. Even with the dealer’s diagnostics options, no statistics regarding previous desulfation systems or the status of Stratified charge (available, turned-off) are available. BMW AG – how so? 

This time, the diagnostics indicated such data too: 

In this menu, we see:

a. Offset value is not confirmed. It is possible it has been incorrect in Overrun mode;

b. the sensor is not Online; it does not send live data. 

And again – no error messages! How so? This is a widespread situation, too. DME (when the working temperature reaches 60 oC, and several other requirements (for example, the appropriate exhaust temperature, RPM, or the driving confirmation) are fulfilled) sends the command to the NOx sensor to turn in Online mode and start to send live data. Correctly performing sensor fulfills this command during 30 .. 60 seconds. But, if the sensor is worn out, clogged, damaged, or China-made “analog,” the Online mode never starts. Not after a minute, not after 5, 10 minutes. And there will be no error message in the error message memory. And again, a question – BMW AG, how so? Why the status of the sensor is not controlled?

To make the situation even more “interesting”, I have to add: China-made sensors are not abiding command of the DME at all! China copiers haven’t found out that the sensor should take commands! Accordingly, the use of these China-made sensors not only doesn’t solve problems with the NOx system – it actually creates other/new/hidden troubles. 

Without any illusions – in this case, the cause of the problem is the NOx sensor. Have to mention that there are too many surprises happening. For example, ISTA (the only diagnostics tool available for the dealer’s personnel) displays the status of the NOx sensor for the N43 series engine incorrectly. Whatever the real state of the sensor, ISTA indicates “Expecting Dew Point”. In addition, not for N43, not N53, not in ISTA or INPA, the sensor status, required by DME, is shown – the diagnostic specialist (unless he/she has reverse-engineered the entire system) has no clarity, should the sensor be in Online mode or not. BMW AG – how so?

The short summary (let’s assume I’m an employee of the BMW AG dealer center): the problems with the NOX converter are not visible. Its remaining capacity is unknown. Problems with the NOx sensor are not visible. In the case of the N43 series engine – even the status of the NOx sensor is not visible. Conditions by which the NOx sensor should be Online – are not mentioned anywhere. Even more – it is not mentioned anywhere that the sensor works in different modes (Offline, Online, etc.). I researched all this myself by reverse engineering the system. 

Let’s assume I’m an employee of the BMW AG dealer center with enormous experience. When I hear the reclamations regarding increased fuel consumption, I immediately suggest – performing the desulfation session! My experience says if the Stratified charge is turned off, the simplest and the cheapest cause – a contaminated NOx catalytic converter. 

This suggestion/solution was tested by the owner of this vehicle too. The result: 

The desulfation session was activated by using INPA. For a longer time, the speed was higher than 120 km/h. Unfortunately, the exhaust temperature did not reach more than 350 oC; Lambda stayed at 1.00 all the time. Level of contamination: 462 mg, and it did not even think of decreasing it. DME wasn’t even thinking of starting the desulfation session! 

It’s a complete dead end. The employees of the dealer center could only shrug their shoulders. 

Why didn’t DME start the desulfation session? Due to hidden problems of the NOx sensor. DME sees that the sensor is not Online, and due to this, the required desulfation session was canceled. 

To my objections that the vehicle has problems with the NOx sensor, the owner objected that the sensor had been replaced a little while ago. Was the OEM sensor installed? Unfortunately, no. The cheapest “analog” was. Here is the cause of the problems with the sensor. 

True, though, even with installing the OEM sensor, the problems will continue. The NOx catalytic converter is so worn out that with zero illusions, the error message 30E9 will appear soon. When this error message is recorded, the only solution will be the replacement of the NOx catalytic converter (investment of at least EUR 7000). Or NOXEM.

In conclusion, related articles: With the N53 series engine for the F series, the situation is even more “fun”. Here and here, I offer you to get acquainted with how BMW AG decided to hide the problems of the F series engines. 

Here is an example of why the diagnostics of the BMW AG dealers are helpless. 

Here, you will find the performance test of the China NOx sensors; here and here – experience using China-made sensors. 

What are the consequences of a turned-off Stratified charge? Read here.