حساس ضغط هواء حقن محلول المعالجة معيب

On air-assisted reductant systems, the sensor watching the compressed air that atomises the fluid before it enters the exhaust. Only some systems use air assistance at all, which is worth establishing first — on an airless system this sensor does not exist and the code names something else entirely.

Atomisation is the reason the air circuit matters. Reductant delivered as a fine mist evaporates and reacts; delivered as a stream it lands on cold metal and crystallises into a hard deposit that blocks the injector and coats the catalyst face. So a fault in the air pressure reading is not a monitoring inconvenience — the module uses it to decide whether dosing is safe, and it will stop dosing rather than risk the deposit.

The circuit around it fails more often than the element. It sits in a hot, vibrating, salt-exposed position, so a chafed harness, a corroded pin or a cracked air line reaches it first. Check the air line for a leak or a blockage while the connector is off, because a genuinely low air pressure and a sensor misreporting it produce the same code and the line is the quicker of the two to rule out.