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Peugeot Boxer Emissions Fault — Investigation & Resolution

2019 Peugeot Boxer 2.2 BlueHDi 140 (Euro 6)· High Wycombe, Buckinghamshire

Intermittent limp mode, no warning lights at rest — a classic Boxer P2200 / P2202 pair, hiding behind a wiring fault.

Reported symptoms

  • Intermittent limp mode under load (motorway hills)
  • EML clears itself after restart
  • No countdown initiated
  • Owner reported 'phantom' fault that dealer could not replicate

Diagnostic process

  1. Diagbox scan recovered P2200 + P2202 in history with intermittent flag
  2. Loom inspection at upstream NOx sensor connector — chafed wire near heat shield
  3. Live data wiggle-test reproduced signal drop
  4. Confirmed sensor itself within spec once wiring corrected

Findings

A chafed signal wire on the upstream NOx sensor harness was intermittently shorting against the heat shield under thermal expansion. The fault only appeared at sustained load, which is why it presented as 'phantom' at idle.

Resolution

  1. Repaired and re-loomed signal wire, added abrasion sleeve
  2. Re-secured harness clear of heat shield
  3. Reset adaptations and cleared codes
  4. 60-minute motorway road-test to confirm no recurrence

Outcome

Boxer returned to its delivery route the same evening. No NOx sensor replacement required — wiring repair only. No recurrence at 5,000-mile follow-up.

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Case study FAQs

Intermittent NOx wiring faults often only present under sustained load and heat — a five-minute static diagnostic at the dealer rarely triggers them. A proper road-test under load is essential.

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