Almost in all entries, if they are somehow related to the repair of the engine, I mention: perform the re-adapting of the engine. If it’s performed using INPA, and the car has an OEM NOx sensor installed, before the re-adapting, the desulphation of the NOx catalytic converter should be performed.

It is possible, that many people think – you can skip these procedures because “the engine will learn itself”. I am aware, that many service centers (even specialized BMW service centers) don’t perform the re-adaption of the engine, not even talking about depuration (desulfation) of the NOx catalytic converter.


In this entry – one of many examples, how such an unprofessional attitude (failure to follow the service procedures) ends.


Patient: E90 with an N53B30U0 engine.

The NOx sensor replaced one year ago, 9 months ago – all injectors replaced. I doubt, that the replacement of these elements was really necessary (especially – the replacement of ALL injectors), but – what’s done, it’s done. Even more – the mileage of the vehicle is around 140’000 km. What could happen to the injectors (ALL of them) by such low mileage? Read on – the situation is quite educating.

The valve cover with CCV also was replaced. Yes, it could be, that during 10 years the CCVV membrane has become fragile, and the airtightness around its perimeter is gone.

Complaints of the owner of the car: fuel consumption around 9l/100km, driving on the highway; even after short rides the inside of the exhaust pipe is covered with black residues (obviously, the fuel mixture is enriched).


Checking data of INPA, have to conclude some strange things:

a) the engine has NEVER used Stratified charge (../F5/Shift+F6/F2, first 2 learnbits of the 2-nd column are not colored);

b) it’s confirmed by ../F5/Shift+F6/F5 menu – both idle and partial load data are 0: the injector tests in Stratified charge are NEVER performed;

c) at the same time – the NOx sensor is Online, its data – correct ../F5/Shift+F2/F1;

d) in Homogeneous mode, the engine has troubles to balance the idle – mechanical efficiency of the 4-th cylinder – increased;

e) not offset, neither multiplicative individual adaptations are applied to the injectors in Homogeneous mode – ../F5/Shift+F6/F1. There is no doubt – the engine works in limp mode.


Here, the appropriate images. Incorrect values marked with red circles.

What could happen to the engine? Why the DME uses limp mode?

Here, the explanation: in History memory, the record of the 30EA error message is seen. True thou – the Error list is empty: obviously, somebody it deleting it diligently.

And here, the contamination of the NOx catalytic converter:

From this data, I make conclusions:

a) when the error message 30EA was detected, this error message was simply deleted – the NOx catalytic converter was not desulphated. If the error message 30EA is deleted, it can not appear repeatedly, but the problem will not disappear – the NOx catalytic converter needs to be depurated. DME forbids Stratified charge until this procedure (depuration) is performed; the engine experiences all problems, which are typical in case of damaged NOx system;

b) after the repair of the engine (replacement of injectors and CCV), the readaptation of the engine has been not performed. If it would be done, the specialist with an appropriate qualification would notice, that the engine doesn’t use Stratified charge (it can be seen, of course, also in INPA and ISTA) and would have started to solve the problem;

c) if the calculation of the contamination of the NOx catalytic converter would be stuck (and the error message 30EA is recorded) by such a small contamination level (only 200 mg), have to conclude, that the performance of the NOx catalytic converter is already critically low. With a high probability, in the nearest future, the DME will record the error message 30E9 (insufficient performance of the NOx catalytic converter)  – and this error message will be justified.


How such inappropriate maintenance of the engine increases the repair costs?

Even if we assume, that the NOx sensor was truly damaged and its replacement was justified, all further actions of the “specialists” only increased the costs of the vehicle owner:

a) as the desulphation of the NOx catalytic converter was not performed immediately after replacement of the NOx sensor, the error message 30EA (which is almost always recorded in case of the damaged NOx sensor) remained active, the engine was not using Stratified charge;

b) DME was not measuring the parameters of the injectors (part of them is measured in Stratified charge, which was forbidden), the fuel consumption of the car – increased. The differences of the injector parameters were not compensated, misfires and vibration started. These symptoms cost around EUR 2000 to the owner of the vehicle, although (with a probability of 99,9%) the injectors were in good condition. Yes, if the Stratified charge is turned off, the indication of some leaking injector problem is significantly more problematic (because there is no data regarding injectors and their “state of health”), but the cause of this problem is inappropriate maintenance;

c) yes, the parameters of the new injectors during their first life stage correspond to the parameters, specified by the manufacturer, so even without individual adaptations and applying of the corrections the engine will work quite satisfactory, but as we see – the fuel mixture is rich, the mechanical efficiency of the 4-th cylinder – incorrect. The engine vibrates and damages the exhaust system;

d) all the time, when the error message 30EA is active, the engine doesn’t use Stratified charge, its NOx catalytic converter is not cleaned and continues to clog up. In this current situation, according to the contamination data, the NOx catalytic converter is damaged. It is an expensive part, which costs more than EUR 2000.


My evaluation of this situation is quite harsh – due to incorrect service procedures:

a) losses for the customer – around EUR 4000 (6 injectors + NOx catalytic converter);

b) expected future expenses (because either the NOx catalytic converter should be replaced, or the NOXEM should be installed);

c) at least for one year the engine has worked in limp mode, with increased fuel consumption;

d) the lifetime of the CO catalytic converters is significantly reduced.

I hope, that this example will convince you – there are no minor nuances in the maintenance of these complicated engines!