Published on 2026-09-14
P2002, P0401, P0299, P0087, P1351… France's diesel-heavy fleet produces a very different code list: DPF, EGR valve, turbo and glow plugs.
France still runs a heavily diesel fleet, and that completely changes the ranking of fault codes. Catalytic converters aren't the main story here — the diesel particulate filter, the EGR valve and the turbo are.
P2002 / P2463 – Diesel particulate filter efficiency / soot accumulation. Number one in France, especially on city cars doing short trips where regeneration never completes.P0401 / P0402 – EGR flow insufficient or excessive. Carbon-clogged EGR valve, extremely common.P0299 – Turbo underboost. Split boost hose or seized variable geometry.P0087 – Fuel rail pressure too low. Clogged fuel filter or tired high-pressure pump.P1351 / P0380 – Glow plug circuit. Hard cold starts.P0420 – Catalyst efficiency. On petrol engines.P2452 – DPF differential pressure sensor. Blocked pressure lines.
These are also the faults that fail the French roadworthiness test (contrôle technique): with tighter emissions rules, an illuminated engine light or a failing DPF means a retest. The ChatMecano OBD2 connector reads active and pending codes, and the AI assistant explains likely cause, severity and the order of checks. See AI Check Engine OBD2 analysis.
Tip: on a city diesel, watching DPF soot load before the light comes on often saves the filter with a simple highway regeneration instead of a replacement costing over €1,000.
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