smartmaniacs.co.uk/forum/the-cars/fortwo-451-sept-2007-present/58570-cdi-dpf-tech-question

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Forum thread: CDi DPF tech question -

smartmaniacs.co.uk/forum/the-cars/fortwo-451-sept-2007-present/58570-cdi-dpf-tech-question · p. 1 · Applies to: 451

smartManiacs Source: smartmaniacs.co.uk Topic: DPF regeneration behavior and maintenance Models discussed: 451 Solution status: yes

Problem: Smart Fortwo 451 CDi with DPF: idle revs rising to ~1100 rpm when stationary in traffic, behavior during DPF regeneration cycles, and concerns about DPF maintenance and removal.

Solution: DPF regeneration is normal operation - a pressure sensor pre-DPF detects blockage; when pressure rises, the engine runs rich to increase exhaust temperatures allowing the DPF to heat up and regenerate. Idle rev increases during regeneration are expected. An exhaust temperature sensor replacement resolved engine management light issues and improved regeneration behavior. Users can monitor oil levels (may rise during DPF operation) and allow regeneration cycles to complete over multiple journeys if necessary. DPF removal via software remapping is available from tuning specialists but optional.

Key facts: - DPF regeneration causes idle revs to rise to approximately 1100 rpm - Pressure sensor pre-DPF triggers regeneration when blockage detected; engine runs rich to increase exhaust temperature - During regeneration, transmission may require higher minimum revs (around 2000+ rpm) before allowing gear changes - Exhaust temperature sensor failures trigger engine management light and impact regeneration cycles - Oil levels may rise during DPF operation - monitoring recommended - Regeneration cycles can continue over multiple journeys or overnight if started during short trips - DPF software removal/deletion available from professional tuning shops for improved power and fuel economy