Adblue System Malfunction – No Error Code or 28653 / P204F (Solution)

dieselschrauber

Adblue System Malfunction – No Engine Start within 1000 Km

If this message appears on the instrument panel, the following procedure can lead to success:

In the A5 Cabrio, 2.0 TDI, CNHA, the warning message appeared due to a leak in the injector's reducing agent ring seal. (Clamp and seal ring replaced - Injector cleaned)

In the Error Log, the following entry was found:

28653 – Reduction System Bank 1
P204F – Unconfirmed Error

The error can be deleted and will not reappear. The error message in the KI still persists. (Even after a 50 km test drive.) There are two (more or less helpful) TPIs on this topic.

TPI 2040064/15 Software error Engine control unit Affects A4, A5, Q5, A6 possibly. Update the software.

TPI 2045062/3 AdBlue System failure - no error entry / error message in the KI.

The latest TPI indicates that the error may have been deleted but is still stored in the control unit. The error can no longer be fixed using the guided troubleshooting procedure but only with a separate diagnostic program (ODIS). (This is stated in the TPI

)

Please check the values after IDE 08132 SCR Inducement DFCC. Does the value 28653 appear here, then the error message reset due to the missing effectiveness was prevented.

For the A5, there is no "SCR Efficiency Check" dropdown field in the VCDS basic settings.

Therefore, incentive trip will be conducted:

- Atmospheric pressure > 877 hPA
- Ambient temperature > 7 degrees
- System Error-Free
- Coolant temperature > 60 degrees
- DPF Load < 24 g

Conduct a constant speed run so that the maximum speed in the highest gear is 1800 RPM.
SCR Kattemperatur between 210-350 degrees
ACC / GRA disabled
Maintain a speed between 1400-1800 RPM.
Motor Torque between 80-270 Nm

If all conditions are met – maintain a 5 sec sailing profile and then abruptly transition to full throttle. (Sail completely off the gas). The diagnosis should be made now.

If the efficiency is satisfactory – the message is immediately cancelled.

The A5 is back in action...

Best regards

Michael