Mercedes AdBlue Level Cannot Be Determined – Diagnostic Guide
DESCRIPTION
Guide explaining common causes of the Mercedes “AdBlue Level Cannot Be Determined” warning, including SCR system faults, AdBlue tank level sensor issues and emissions system communication faults.
DIAGNOSTIC INSIGHT
The “AdBlue Level Cannot Be Determined” warning is commonly triggered when the SCR system cannot accurately calculate the AdBlue level or detects a fault affecting the AdBlue system.
In many cases, the issue may relate to:
- AdBlue level sensor faults
- faults within the AdBlue tank assembly
- SCR system communication faults
- NOx sensor or emissions-related faults preventing correct system operation
The warning may appear before a restart countdown or engine warning light becomes active.
Live diagnostic testing is required to identify the root cause before replacing components.
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IMPORTANT NOTE
On many Mercedes models, the AdBlue level sensor is integrated into the AdBlue tank assembly and may not be replaceable separately.