Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 present in AdBlue (SCR)...

Bulletin number

LI4920N078838

Component

Engine

Summary

Check engine light or Adblue warning with fault codes P206B31, P203B31, or P300494 present in AdBlue (SCR) control unit (N118/5) Complaint The check engine light or AdBlue warning is activated, accompanied by one or more of the following fault codes related to the AdBlue tank: P206B31: Malfunction of the concentration sensor for AdBlue; the signal is absent. P203B31: Malfunction of the AdBlue fill level sensor; the signal is absent. P300494: The quality of the AdBlue is insufficient. Cause A. The software for the AdBlue (SCR) control unit (N118/5) is outdated. B. The concentration of AdBlue is either above or below the Mercedes-Benz specifications, which can lead to premature freezing. C. Frozen or partially frozen AdBlue can cause the AdBlue level sensor to misread levels. D. The AdBlue level sensor is damaged.

Owners of these vehicles have filed 25 complaints in the engine category.