FAQ
TL;DR: 73 % of Boxer/Jumper AdBlue failures are traced to one 10 kΩ sensor; “swap a €0.10 thermistor, save a €900 tank” [Elektroda, mako122, post #20290653] Fix takes 30 min with basic tools and stops P20E8 low-pressure errors.
Why it matters: A single DIY repair prevents immobilisation and four-figure garage bills.
Quick Facts
• Urea freezes at −11 °C, so Peugeot/Citroën tanks contain 7 heating circuits [Elektroda, mako122, post #20319592]
• Plate-heater resistance: 1.3 Ω; pump heater: 55 Ω; line heater: 2.5 Ω [Elektroda, mako122, post #20319592]
• Working pressure window: 4.9–6.1 bar; ECU cuts pump below 4.0 bar [Elektroda, mako122, post #20339688]
• New OEM tank list price: approx. €900–1 100 [*Stellantis Parts*].
• Dry plate can reach 150 °C in 10 s, triggering instant shutdown [Elektroda, mako122, post #20290653]
What triggers the common P20E8 “urea pressure too low” fault?
In 3 out of 4 cases the heater-plate NTC (yellow wires, nominal 10 kΩ at 25 °C) drifts to ≤1 kΩ. The ECU then disables pump and shows P20E8 even though pressure hardware is healthy [Elektroda, mako122, post #20290653]
How can I test the suspect thermistor without removing the sealed lower tank?
Unplug the grey connector, measure resistance between the two yellow wires. 8–12 kΩ at room temperature is OK; ≤2 kΩ or open-circuit means failure [Elektroda, mlody300, post #21442824]
Quick 3-step fix for a bad plate sensor?
- Cut yellow wires near the board.
- Solder a 10 kΩ, 0.25 W NTC (or fixed 10 kΩ resistor) in series and slide it 10 cm inside the loom.
- Clear DTCs; system self-tests after 15 km [Elektroda, Reflekt, post #20913040]
Will adding a fixed resistor overheat the plate?
No. The ECU still reads the urea-temperature NTC (blue wires) and starts heaters only below 5 °C, so risk of 150 °C dry-plate runaway is avoided [Elektroda, mako122, post #20290653]
Why does the tank lose 12 V feed after 30 s?
After start-up the engine ECU waits ~30 s for CAN feedback. If none arrives (e.g., open heater, bad sensor, CAN line fault) it drops relay RL110 and the supply disappears [Elektroda, mako122, post #20310700]
My live data shows constant 4 bar – is the pump dead?
Yes. The pressure sensor reports 4 bar whenever actual pressure is below its calibrated range. Real working values should cycle between 4.9 and 6.1 bar [Elektroda, mako122, post #20339688]
Can I replace just the pump motor?
The brushed DC motor (2.3 mm shaft) is not sold separately. Easiest option is a €100 used tank and swap the motor & O-rings [Elektroda, mako122, post #20335696]
How do I reseal a leaking pump plate?
Use 22 × 2 mm VMQ and 5.5 × 1.5 mm NBR70 O-rings, plus two 2 × 2 mm shaft rings. Clean urea residues with warm water, assemble cross-tightening screws to avoid cracking [Elektroda, Pablo_Pablo, post #21400608]
Does the ECU need adaptation after fitting a used tank?
No. Just clear stored faults; the CAN ID is not VIN-coded. Only a NOx-system reset/bleed may be required [Elektroda, melas, post #19586250]
What edge-case kills the board even when sensors are OK?
A tiny leak past the 2 mm shaft seal floods the motor, then corrodes the PCB via capillary action. Board swap is the only cure [Elektroda, Pablo_Pablo, post #21400608]
Is software flashing (v3.2→v4.0) mandatory?
Stellantis TSB B1KW017XQ0 (24 Jun 2024) recommends flashing tanks with SW ≤3.2 to stop false P20E8 after heater repair. Dealers use the SCR Tank Flasher tool [TSB extract, 2024].
How do I reset the immobiliser countdown?
Use Diagbox: Global Test → BSI → Maintenance → ‘Delete mileage until engine stop’. On MD1CS069 ECUs you must bypass the SGW gateway first [Elektroda, melas, post #21542794]
Will disabling AdBlue pass inspection?
Many EU countries now check NOx via probe; software delete causes 4–8 × limit emissions and leads to €3 000–12 000 fines [ICCT, 2023].
Injector still clogged after pump fix – what next?
Remove injector, energise with 12 V pulses and back-flush with hot water. Persistent white crystals mean replace (~€120) [Elektroda, pentel, post #21088255]