P2002 on Mercedes-Benz

On diesel A-Class models (A180d/A200d/A220d, OM608/OM654 engines) driven mainly on short, low-speed urban trips, the DPF cannot reach the high exhaust temperatures needed for passive regeneration. Soot accumulates, the DPF/engine warning light illuminates, and the car can enter limp mode with a stored 'soot content too high' fault. A very common complaint among EU-spec city-driven diesels.

The 2.2L OM651 diesel in B180 CDI / B200 CDI variants is prone to diesel particulate filter (DPF) blockage and EGR-valve carbon fouling, especially on short urban trips where the exhaust never reaches regeneration temperature. Symptoms include reduced power (limp mode), increased fuel consumption, frequent failed regenerations, and warning lights. Carbon buildup in the EGR valve and intake also causes hesitation and rough running. The OM651 timing chain can also stretch and rattle, compounding diesel reliability concerns.

GLA diesels (GLA 200d/220d), popular in Germany and the EU, develop clogged EGR valves and diesel particulate filters from soot buildup, plus AdBlue/SCR (NOx reduction) faults. EGR carbon fouling causes rough idle, reduced power and emissions faults; DPF blockage triggers limp mode if regeneration can't complete (common with short urban trips). AdBlue/SCR issues include crystallization from irregular use, sensor/NOx-sensor faults, level/quality warnings and countdown-to-no-start messages. The OM651 also shares timing-chain-stretch tendencies.

EU-market GLS 350d/400d models with the OM656 3.0L inline-six diesel suffer from sensitivity in the exhaust aftertreatment chain. The EGR (AGR) valve, diesel particulate filter (DPF) and SCR/AdBlue system are sensitive to poor fuel quality, short-trip driving and temperature swings. Clogged DPF, a dirty/sticking EGR valve, or a faulty EGR differential-pressure sensor cause power loss, failed regenerations, dashboard warnings and limp-home mode. A German motor-talk owner thread on the GLS X167 400d documents poor acceleration that resolves after a restart, traced to a replaced EGR differential-pressure sensor under warranty. This primarily affects diesels not sold in the US, so it is especially relevant to the EU market.

The Sprinter diesel exhaust fluid (DEF/AdBlue) selective catalytic reduction system is plagued by faults in the dosing module, NOx sensors, DEF heater, and SCR catalyst. Failures trigger the dreaded "engine derate" countdown that limits vehicle speed to 5 mph if not resolved, stranding commercial vehicles. The system is sensitive to DEF quality and cold weather.

Sprinters used for city delivery — frequent stops, short trips and long idles — rarely reach the exhaust temperatures needed to complete a DPF regeneration. Soot accumulates until the filter is restricted, lighting the DPF warning, reducing power and eventually forcing limp mode with a speed limit. This is one of the most common operational complaints for urban-duty European-spec diesel vans.

The Euro 6 diesel particulate filter on the W447 needs periodic high-temperature regeneration to burn off soot. V-Class vehicles used for short urban trips never reach regen temperature, so soot accumulates, regen attempts fail, and the DPF eventually clogs. This brings warning lights, sluggish performance, increased fuel consumption and limp mode (capped around 2,500 rpm). The aggressive Euro 6 emissions hardware makes the W447 particularly sensitive to short-trip duty.