Mercedes Adblue fault – Mercedes Xentry Guided Procedure

After performing a number of AdBlue fixes on behalf of local Mercedes specialists we have since released the technical procedure / guide so both our customers and other Mercedes specialists are able to effectively diagnose and cure the dreaded Mercedes AdBlue fault.

Mercedes specialist
Mercedes specialist

Engine diagnosis warning lamp lights up.
“Check AdBlue” or “No start in XXX km (miles)” appears in the instrument cluster and one or more fault codes concerning the AdBlue system are stored in the engine control unit.
A distinction is made in the fault codes between system fault codes and cause fault codes.
Possible system fault codes are: 16D300, 16D400, 16D500, 15EA00, 15EB00, 15EC00, 16CE00, 16CF00, P13DF00,
P13E300, P13E400, P13E500, P13DF09.
These system fault codes are always shown together with at least one cause fault code in the engine/SCR control
unit. The quick test must not be erased otherwise the information on the cause fault code will be lost.
Important: If an active system error is present, the AdBlue tank must not be filled.
After processing the cause fault(s), the AdBlue fill level must be checked. If the fill level is correct, then it does not
need to be topped up to rectify the fault!!
The cause fault code must first be rectified in the engine control unit with the guided Xentry Diagnostics test in order
to enable the system fault code “AdBlue” to be erased.
Note: The latest Xentry Diagnostics DVD must be installed.
Once all the cause faults have been rectified, the quick test can be erased.
Note: When the quick test has been erased, the existing system fault code and the combined message “Check AdBlue” or “No start in XXX km” will remain active.
To erase the system fault code and the combined message, proceed as follows:

  • Check that the engine and BlueTec control unit software is up to date
    Note for vehicles with engine 642 (except model series 463): With add-ons 3505, 3605, 3622 (DVD01/14) and 3506,
    3606, 3623 (DVD03/14), new engine control unit software is available for vehicles with modification year (YoM) codes
    801 and 802 which supports the resetting of system faults via Xentry Diagnostics.
    Note for vehicles with engine 651 or 642 with YoM code 803 and higher: Resetting of system faults via Xentry Diagnostics is generally supported.
    Procedure: Resetting a system fault code with Xentry Diagnostics
    Proceed as follows:
    => Launch the guided test behind the system fault code and then immediately click on the link “Reset warning message…”.
    If “Completed successfully” is shown, the system fault can be erased. An additional adaptation test drive is no longer
    It is only necessary to perform an adaptation test drive to erase the system fault code if the message “Reset not completed successfully” appears.
    The adaptation test drive must be performed according to the following criteria:
  1. Warm up the vehicle for approx. 10 min (coolant temperature at least 80°C/176°F, catalytic converter temperature
    at least 250°C/482°F)
  2. Drive for 30 min as consistently as possible between 80 km/h (50 mph) and 120 km/h (75 mph) with occasional
    coasting phases.
    Then check whether the fault is set to “stored”.
    If so, erase the fault; the message in the instrument cluster disappears.
    If not, perform an adaptation test drive according to the following profile:
  3. Drive for 5 min at a constant speed (no throttle blips, no acceleration) between 80km/h (50 mph) and 90 km/h (56
  4. After 5 min gradually increase the speed to 100 – 110 km/h (62 – 68 mph) and then coast for approx. 15s – 25s. After the coasting phase, gradually accelerate again to 100 – 110 km/h (62 – 68 mph) and repeat the procedure another
    5 times.
    If the message in the instrument cluster continues to appear, stop the vehicle and switch off the ignition for 5 minutes
    (ignition key removed, no diagnostic equipment connected).