This time – a concise entry is dedicated to the versions of the error message 30DE.
After 2 years of using the NOx sensor, the error message 30DE was recorded in the DME error message memory. Here are the attributes of the error message:

With yellow, the Lambda values in both banks when recording the error message are recorded. As we see, the engine has worked in Homogeneous lean (not Stratified charge) mode. Below, you know the reason for this error message: the regular recorder error message 3104 (the most popular reason is misfiring).
With red, the indication of Lambda of the NOx sensor is recorded; it is decreased – much closer to the value of the Homogeneous mode.
Live data shows the following picture:

The Lambda, reported by the NOx sensor (both Binary/Narrowband and Linear/wideband), is correct when the engine runs in Homogeneous mode.
The offset value in overrun mode (marked with yellow) is increased (NOXEM is installed on the current car); in the present case, it means – the sensor’s probe is clogged, or any of the injectors is leaking in the closed position.
Analysis of other data confirms that the injectors (at least at this moment) are not leaking; the low temperature of the exhaust (only around 145 oC) gives indirect indications to that.
The owner of the car informed me that the engine has significantly increased oil consumption. Most plausible cause – exactly the oil consumption will be the culprit this time. The oil residue has mechanically blocked the air access to the cells of the probe. In a very narrow range (with Lambda around 1.00), the probe indicates correct values, but the air is not “sensed” by the larger intake of air.
Unfortunately, the miracle did not happen. A short-term solution – replace the probe of the NOx sensor. The solution to the cause of the problem: oil consumption – could turn out much more challenging. In the most optimistic scenario: the CCV defect, but most probably – wear of the engine piston group. In a second case, the investments in the repair of the engine will be impressive.