What damages NOx catalytic converter

The NOx catalytic converter is an expensive spare part (it costs at least EUR 2000). Unfortunately, there are many cars, in which this catalytic converter is damaged already by mileage of 100 .. 120.000 km.

What confirms damage of the NOx catalytic converter? The error message 30E9.

This error message, unfortunately, can not be deleted, only replacement of catalytic converter or installation of NOXEM will help.


What damages NOx catalytic converter?

1. Fuel with increased content of sulfur. Exactly the sulfur damages the NOx catalytic converter. Unfortunately, when you are filling the fuel, there are no signs, that would indicate – this fuel (manufactured by the exact manufacturer, or – from the exact batch) has increased content of sulfur. It is highly possible even the petrol station or the delivery company don’t know about the problem in an exact batch. Unfortunately, there is no way, how we – car owners – can secure ourselves against alow-quality fuel;

2. Inappropriate driving profile. N43/N53 engines are developed for long drives. Exactly for this reason, a special accent is put on the economy. But for NOx coverter to be able to work properly, it has to be regenerated regularly. This regeneration in a normal situation is an automatic process. The only requirement – the car has regularly driven with at least 110 km/h for a sufficiently long period of time (several minutes won’t be enough). What shows the NOx catalytic converter is not regenerated? The error message 30EA. If this error message regularly appears in the error message memory of DME – wait for trouble.

3. Defects of the NOx sensor. If the NOx sensor is damaged, the NOx catalytic converter is not regenerated. In this case, no error message 30EA will be recorded, which could indicate problems with the NOx catalytic converter. Even more – there can be no error messages regarding the NOx sensor itself! Unfortunately, such a hidden defect is so common, sooner or later it affects practically every car, which is equipped with N43/N53 series engine. The only method, how to make sure the NOx sensor works as it’s supposed to, is:

a) warm up the engine, check the temperature of the exhaust (it has to be at least 220 oC);

b) perform a short driving session with a speed of 20 km/h;

c) wait for 1 .. 2 minutes;

d) check indications of the NOx sensor, using ISTA D or INPA.

It’s clear such inspection can be done only in case, you have an appropriate diagnostic tool and knowledge. In addition, this defect of the NOx sensor can be (and usually it is) sporadic, which means – without a visible cause the sensor can turn on, and then turn off after a moment. Accordingly – even if the owner during one driving session sees correct performance of the sensor, it doesn’t means correct performance at the next session, or even after 5 minutes!

4. Increased oil consumption. Also increased oil consumption damages NOx catalytic converter. The typical cause of increased oil consumption for these engines – damaged CCVV. This problem (increased oil consumption) has to be eliminated as soon it is detected because the oil in the exhaust damages also CO catalytic converters, Lambda probes, and NOx sensor. An acceptable oil consumption – around 1 liter/3000 km.


And finally – situation, where the manufacturer of the car cannot be blamed. Quite often we can see cars with a modified odometer indication. Be careful – the car with reduced mileage can have not only problems with NOx system! Many other hubs also will be worn out more than expected!