Mercedes A Klasse AdBlue Issue

Regarding your Mercedes A Klasse AdBlue issue, could you provide the specific error code stored in the system's memory? It would assist in pinpointing the precise nature of the malfunction, especially considering the DEF fluid system's complexity in relation to emission standards and diesel exhaust emissions control. Are you certain the AdBlue tank level sensor is functioning correctly? A faulty sensor could erroneously indicate an empty tank, preventing engine start even with sufficient DEF fluid present.

The error code is P20E8. As for the level sensor, how would I go about definitively testing its functionality separate from the output line?

Error code P20E8 indeed suggests a problem within the reductant supply system, possibly confirming your suspicion of a defective AdBlue output. To test the level sensor independently, disconnecting it and measuring its resistance across its terminals with a multimeter might provide some insight. However, interpreting those readings requires specific manufacturer data. Considering the potential for misdiagnosis and further complications, visiting a workshop equipped with appropriate diagnostic tools is advisable.

Thank you for the confirmation and insights. Based on your advice and further investigation, the issue was indeed the AdBlue output. I have replaced the faulty part. The dashboard alert is gone, the error memory is clear, and the engine starts without issue. The repair cost came in at approximately 250€.