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Troubleshooting AdBlue P20E8 and P20A2 on a Peugeot

Model: Peugeot 308 P5, MK 3 - Years: 2021, 2022, 2023, 2024, 2025, 2026
Part: AdBlue warning light

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Video tutorial

In this video, we see that the previous owner of this Peugeot resolved their issues with the AdBlue control unit by disconnecting the contacts: unfortunately, this is a solution that many desperate Peugeot owners adopt, but it is not the correct one. Instead, here’s how to proceed: with the P20E08 error, the only option is to replace the tank, but first, remove the control unit, check it through the electronics, and restore it to the original Peugeot factory settings, then put it back in place, and change the AdBlue tank.

Next, reset the error using the EOBD tool (of course, we do this with professional equipment).

The AdBlue starts to function after the catalyst reaches 200°C, so to see the problem, we need to heat the catalyst properly; otherwise, it won’t show any issues. We fully agree that the used vehicle being sold must be original, with no strange modifications made by users.


Updated on 31 August 2026 by ScegliAuto


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Watch the video!


by ScegliAuto

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