The topic for today:

30EA nitric oxide catalytic converter, sulphurized

The sulfur damages NOx catalytic converter. For this reason (fuel can contain a huge amount of sulfur infusion), BMW vehicles with N43/N53 engines are not available in such global markets as USA, Russia, Africa. And exactly for the same reason is very important to use only high-quality fuel without sulfur, if you drive the car with an N43/N53 engine.

MSD80 records 30EA error message, if the determined (mathematically counted and measured using NOx sensor’s data) parameter of sulfur “poisoning” is higher than the allowed limit, and the regeneration or catalytic converter is not performed/not possible.


Poisoning of NOx catalytic converter is calculated summing up two values:

a) mathematically counted possible “poisoning”, proportional to burned fuel;

a) real efficiency and “poisoning” with sulfur (from fuel) of catalytic converter – performance reduction (measured by NOx sensor).


Causes for such situation (recording of 30EA error message) could be:

a) driving profile. N43/N53 requires periodically increased speed 110+km/h to perform desulphation of NOx catalytic converter;

b) incorrect performance of NOx sensor (defect – lowered response of the sensor, no errors stored);

c) damaged NOx sensor; damaged exhaust temperature sensor (corresponding errors stored in MSD80 memory).


In all cases – for some reasons, desulphation of the NOx catalytic converter is not performed within acceptable terms after reaching the request for desulphation.

Note: For a brand new NOx catalytic converter desulphation request (critical value) is recorded after 3000 .. 4000 mg (6000 .. 8000 km between desulphation sessions). If MSD determines the reduced efficiency of the NOx converter, desulphation request (and error message 30EA) can appear more quickly (even after 1000 .. 1500km and 600 .. 700mg).


Note: 30EA can be stored into Info list too: ../F4/F2/F1. If 30EA is cleared, the problem becomes invisible – 30EA is not stored repeatedly, at the same time: Stratified charge is disabled (and all problems described here appear).

Attention! The average lifetime of expensive NOx catalytic converter is around 150.000km. If the NOx sensor is damaged, the engine management system MSD80 cannot determine the remaining capacity of NOx catalytic converter and error message 30E9 about the aging of NOx converter will NOT be stored even in a situation if NOx catalytic converter is damaged. This message (and all consequences – increased fuel consumption, rough run, misfires) will appear after replacement of NOx sensor (if brand new OEM sensor will be installed). If mileage on your car exceeds 150.000km we recommend using NOXEM even if the 30E9 error is not stored. NOXEM will restore full performance of your car’s engine even if NOx catalytic converter is aged, damaged or removed.

Short about specific problems with NOx sensor. If the measuring ‘head’ (very accurate and sensitive measuring tool) of NOx sensor is clogged up – the performance of NOx sensor slows down and also its signal’s deviation slows down; after regeneration phase this signal fails to drop till “0” level. By this reason, MSD80 considers, that the NOx catalytic converter has lost its performance. Also, if NOx sensor’s ‘head’ is aged, the sensor can stay in ‘Not Ready’ mode for a while, no errors are stored in MSD80 memory, but Desulphation sessions are disturbed.

Incorrect data of NOx sensor (the NOx sensor reports decreased ability of converter to regenerate after short regeneration phases, which MSD80 understands as performance reduction of catalytic converter and a need to perform the desulphation session) can be the reason of quick increase of calculated poisoning amount of NOx catalytic converter regardless of acceptable performance of NOx catalytic converter, as the result – also 30E9 error message can be stored.

If NOx sensor is damaged (and corresponding error messages relating NOx sensor stored in MSD80 memory, for example: 2AF2; 2AF4; 2AF6, full list available here), desulphation sessions are disturbed and 30EA will be recorded after few thousands of km regardless of real performance of NOx catalytic converter and driving profile (even if necessary driving speed for desulphation is reached regularly).


Important. After replacement of damaged NOx sensor:

All four procedures and their sequence is critically important, without encoding of new NOx sensor, erasing of error messages, cleaning of NOx converter and re-adaptation of the engine, the engine will not restore normal operation.

How to check the performance of NOx sensor, read here.


If MSD80 registers error message 30EA, it:

a) don’t allow nor Homogeneous lean, nor Stratified charge mode;

b) the engine slowly loses long-term trims and is not able to create new long-term trims (exactly the same in case of error message 30E9); rough run, misfires appears; also error messages relating fuel trim, CO converters, Lambda probes can be stored;

c) by deleting this error message, it’s not restored in error message menu (as it happens with error message 30E9), but it is stored/can be found in info and/or history memory section, using INPA. If 30EA is deleted from error memory list, ISTA D don’t give any error messages regarding MSD80, but the active status of 30EA is kept and all problems continue;


Poisoning of NOx catalytic converter can be observed using INPA (../F9/Shift + F3/F1)

When poisoning of NOx catalytic converter reaches 400 .. 1000 mg (values for aged/brand new NOx converter), MSD80 tries to start desulphation sessions when driving speed reaches 130 .. 140km/h. When poisoning reaches 600 .. 2000 mg, necessary driving speed to starting desuphation decreases to 110 .. 115km/h. If desulphation were not possible until poisoning reaches 700 .. 3000 mg, MSD80 stores 30EA error message and stops attempting to perform desulphation of NOx catalytic converter. Detailed information about desulphation of NOx catalytic converter can be read here (second part of blog entry).


What to do, if 30EA is stored?

First of all – check the performance of NOx sensor (as described here), even no errors are stored in MSD80 memory. If problems are identified, replace and encode new NOx sensor as mentioned above.

Then – proceed forced Desulphation (cleaning) session.


Forced cleaning (desulphation) of NOx catalytic converter requires:

  • fill fuel tank at least for 1/2;
  • activate forced desulphation session using INPA or ISTA D/+;
  • drive a car with speed at least 110km/h for at least 30min*

*remaining poisoning value after desulphation session: 30 .. 40%


Activation of forced desulphation session can be done using INPA or ISTA D/+.

  • Using INPA: select Desulphation menu (../F9/Shift + F3/F1), press F1;
  • Using ISTA D: perform service procedure ‘Nitrogen oxide catalytic converter regeneration’.

How to activate forced session of Desulphation, read here and here.


Reaching the necessary speed (above 110 .. 115km/h), the engine will try to perform regeneration of NOx catalytic converter. The fuel consumption grows, the temperature of the exhaust system (according to data from a temperature sensor) in cruise speed 110 .. 120 km/h reaches 550 .. 650 oC. Reported Lambda (by sensors) is around 0,94 .. 0,96, which confirms, that unburned fuel is in the exhaust system.

During desulphation session (or right after) remaining poisoning of NOx catalytic converter should be controlled (using INPA or ISTA D/+).


According to BMW regulation (as mentioned above), in such situation, you have to fill the fuel tank, drive for a half an hour at least on 110km/h. Unfortunately, in some countries such speed is above all speed limits, so formally the regeneration of NOx catalytic converter here is not possible. The only one solution in this situation: replacement of NOx sensor with NOXEM.

Important! According to TIS, activation of desulphation session enables ‘more frequent’ cleaning of NOx catalytic converter, not immediate and guaranteed cleaning session! Taking this in to account – control of basic parameters (exhaust temperature, Lambda and poisoning level of NOx converter) is necessary during desulphation session.


Related entries:

Rough run. Trim errors. Hidden cause

NOx catalytic converter regeneration and desufation

Stratified charge performance check

Forced desulphation of NOx catalytic converter