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How to Resolve P0508B AdBlue Error on Citroen C4

Model: Citroen C4 MK 3 - Years 2020-2026
Part: AdBlue warning light

The issue discussed in this video is the emissions fault message, impossible to start in 50 miles: the vehicle still runs but with the prospect of an imminent blockage. Possible causes include: low AdBlue level, faulty tank sensors or exhaust system; a faulty AdBlue pump, or an error in the dosing system (SCR). Simply clearing the error codes with an OBD2 scanner is not sufficient; a professional diagnostic machine like the Launch X431 Pro in the video is essential (which is indeed a very expensive device: available on Amazon with code B07RY6W58R for £869.00). The procedure is as follows: connect the diagnostic machine to the ODB port, turn on the ignition, enter the engine module, look for the "service action" option, go to "emissions control circuit" and select "reinitialise AdBlue system", then follow the on-screen instructions. Turn off the ignition, turn it back on and confirm the operation. This way, the light should turn off and the countdown should reset.

Posted on 17 March 2026 by ScegliAuto

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