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Peugeot 508 AdBlue Problems — Diagnosed & Fixed

Car · 2.0 BlueHDi 160 / 180 · 1.5 BlueHDi 130

The 508 — saloon and SW estate — shares its BlueHDi architecture with the 3008/5008 but typically presents AdBlue faults later (higher motorway mileage keeps SCR healthier). When it does fault, it's almost always a downstream NOx sensor.

508 owners — often company drivers — see the warning, get a dealer quote they're not paying, and find us for an OE-coded fix at a fraction of the price.

Common 508 AdBlue warning messages

  • Risk of no engine start: do not ignore
  • Anti-pollution faulty
  • Refill AdBlue tank

Symptoms 508 drivers report

  • Warning appearing later in the 508's life than in a 3008
  • Repeat fault after non-DiagBox clear
  • Reduced power on cold start

Common causes on the 508

Downstream NOx sensor failure

Dominant 508 fault — sensor ages 70–100k under company-car motorway duty.

Upstream NOx sensor (2.0 BlueHDi)

Less common but appears on higher-mileage cars.

AdBlue tank module fault

Pressure / dosing faults on higher-mileage cars.

Our 508 diagnostic process

  1. DiagBox multi-module scan
  2. Live NOx ppm
  3. AdBlue rail pressure check

Common 508 repairs

  • OE NOx sensor replacement
  • AdBlue tank module replacement where indicated
  • SCR adaptation reset + warning cleared legally

Peugeot 508 AdBlue warning on? Let's get it sorted.

Related services

Peugeot 508 AdBlue FAQs

Motorway-heavy duty cycles keep the SCR catalyst at healthier operating temperatures, slowing sensor drift. Sustained motorway use is the single best thing you can do for AdBlue longevity.

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