Capteur de particules défectueux

The soot sensor downstream of the particulate filter has genuinely failed, rather than being starved of power or fed a bad sample. It is worth being sure which, because the part is expensive and its connector is the commonest culprit — it sits under the vehicle in the exhaust stream, where road salt and standing water reach it in a way nothing in the engine bay experiences.

The element itself fails in two recognisable ways. Its self-cleaning heater degrades, so it never burns its electrodes clean and reports a permanently bridged, meaningless value afterwards; or the electrodes stop accumulating predictably, usually because oil or coolant reaching the exhaust has coated them.

A heater fault stored alongside is the tell that the sensor is genuinely finished, and it usually explains every other code the sensor has set. Where the connector is clean and tight and the heater resistance is out of specification, this is one of the more reliable conclusions in the family.