Diagnostic: DPF warning light on Mercedes - Causes and costs

The DPF (particulate filter) warning light on a Mercedes diesel (A-Class, C-Class, E-Class, GLA, GLC in OM654 or recent diesel engines) means the filter is saturated or a fault (sensor, regeneration) is detected. Mainly urban or short trips can prevent automatic regeneration.

Mercedes: common causes

On OM654 and recent Mercedes diesel engines, the DPF light often comes on because the filter is clogged (regeneration not or barely completed), the differential pressure sensor or probes have failed, or automatic regeneration (post-combustion injection) did not complete. Short cold trips, or low AdBlue level on SCR models, can make the problem worse.

What to do when the light comes on

Follow the handbook: usually a steady-speed drive (main road or motorway, around 2,000–2,500 rpm) for 15–20 minutes to allow regeneration. If the light stays on or flashes: do not push the engine; have it diagnosed (fault codes, differential pressure). The garage can perform forced regeneration; if the DPF is too blocked, cleaning or replacement may be required.

Order of magnitude for costs

• Diagnostic / forced regeneration: about €80–150.
• Differential pressure sensor: about €150–400 (part and labour).
• DPF cleaning: about €200–500.
• DPF replacement: about €1,000–2,200 and more depending on model (part and labour).

My Auto Check-up helps you prepare your visit by describing symptoms for an initial estimate.