Hey folks,
I recently had a weird experience with my 2018 Peugeot 308 BlueHDi that threw a P20E8 code - AdBlue pressure too low. The pump was only pushing 4 bar instead of 6, and diagnostics showed the pump status = stopped.
I didn’t have time to troubleshoot right away, so I kept clearing the code with my scanner. But it came back every 6 km, and after 30 km the check engine light appeared along with the AdBlue countdown (you know the one - car won’t start in X miles 🙄).
Yesterday I finally had time to look into it. I disconnected the battery and started trying to unplug the ECU (EDC17C60) to disable AdBlue via CMD. But the ECU connector lock was super stiff and felt like it was about to break - probably from age or exposure. I stopped before damaging it, planning to check with a buddy instead.
Here’s the weird part:
On the way there, the warning disappeared.
I checked again with my scanner, and the AdBlue pressure was reading ~5.5 bar, and it’s been running perfectly for 3 days now with no errors at all.
So here’s my question:
Could the P20E8 fault have been caused by oxidation or bad contact at the ECU connector? Maybe from water intrusion or age?
I’m wondering if me jiggling the connector just enough made the issue go away - or was it pure coincidence?
Has anyone else had something similar happen with AdBlue pressure faults?
Thanks in advance!
P20E8 – AdBlue Pressure Too Low on 2018 Peugeot 308 BlueHDi… Bad Connection at ECU?
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- Last Post 12 серпня 2025
That actually makes a lot of sense. I've seen cases where oxidation or minor corrosion on the ECU connector caused weird intermittent issues, especially with AdBlue systems. They’re super sensitive to voltage and signal consistency.
Just wiggling the connector could’ve temporarily restored contact. If the pressure came back up to 5.5 bar right after, I’d say the connection played a big role. Might be worth pulling the connector again and using some contact cleaner and dielectric grease to protect it from moisture long-term.
Honestly, sounds like more than coincidence. I had almost the exact same problem with a 2017 C4 BlueHDi — AdBlue fault, pressure too low, countdown started, and nothing helped until I messed with the ECU harness.
These connectors aren’t sealed very well against weather, especially after a few years. Just touching or moving the plug might’ve cleared up oxidation or slightly reseated a weak pin. I’d clean the pins and maybe add a zip tie or light clamp to keep the connector tight.
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