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By: The dash lights up like a Christmas tree: yellow coil, engine outline, and either P2452 or P20E8.
One code blames the DPF pressure sensor, the other calls out the AdBlue NOx sensor, but both trigger limp mode and countdown locks under DVSA’s 2024 enforcement guidance.
Swapping the wrong part costs £300 and doesn’t clear the lamp, so this guide gives a side-by-side comparison, driveway tests you can run with a £40 scanner, and mobile fixes that get the van moving within the hour.
Quick comparison table
| Sensor | Typical code | Where it lives | Main symptom |
|---|---|---|---|
| DPF pressure sensor | P2452 / P242F | Bulkhead, two rubber tubes to exhaust | Soot % jumps to 200 %, instant limp mode |
| AdBlue NOx sensor (pre-cat) | P20EE / P207F | Screwed into downpipe, 22 mm head | SCR efficiency low, “Check AdBlue” lamp |
| AdBlue NOx sensor (post-cat) | P20F6 / P229F | Behind the DPF can | Dash says “No start in 500 mi” |
How the DPF pressure sensor fails
The sensor reads exhaust pressure before and after the particulate filter then calculates soot load.
Soot builds, pressure rises, ECU triggers regen.
Rubber tubes crack or fill with moisture; the sensor sees zero flow, sets P2452, marks soot at 200 % and slams the van into limp.
Quick test: pull the two tubes, blow through them — if one’s blocked, you’ve found the issue.
With the engine idling, live data should show 0–2 kPa; anything over 5 kPa at idle means the filter is genuinely blocked.
How the AdBlue NOx sensor fails
Each Euro-6 van carries two NOx sensors.
They heat to 750 °C and sniff exhaust gases; if the post-cat sensor still sees high NOx, the ECU thinks the SCR isn’t working and logs P20EE.
Common killers: heater element burnout, wiring chafed on the heat shield, or water-ingress where the plug hides above the gearbox.
Quick test: key on, measure heater current in live data — healthy draw is 4–6 A.
Zero amps equals a dead heater.
Another clue: the connector boot melts; if the rubber is crispy, expect failed wiring.
Pick the right fix first time
If pressure tubes are clear and live data still shows wild soot %, swap the DPF sensor (two bolts, ten minutes).
If NOx heater current reads zero, save time and replace that sensor instead of dosing pumps or injectors.
Still unsure? A mobile visit clears both doubts and codes:
- Live pressure vs flow check on site
- Heater current test through Autotuner
- On-van SCR software flash if the sensor is healthy but the map is corrupted
Book a technician direct to your yard via the mobile AdBlue removal service or dive deeper into specific Sprinter codes in the fault-code library.
Need the correct sensor fitted today?
07503 134 362 | ✉ info@adbluespecialist.co.uk
Frequently asked questions
Can I drive with a dead NOx sensor?
Yes, but the ECU will overdose AdBlue and soon set a “No start” lock.
Will cleaning the DPF tubes fix P2452?
If moisture or soot blocked the hose, yes. Cracked sensors need replacing.
Do both sensors cost the same?
No. DPF pressure sensors are ~£45 aftermarket; NOx sensors are £180–£320.
