Faulty Secondary Air Pressure Sensor
Secondary Air Pressure Sensor harness is open or shorted
Secondary Air Pressure Sensor circuit poor electrical connection
Engine Light ON (or Service Engine Soon Warning Light)
The AIR system refers to an emissions control system used by some vehicle manufacturers. It is often called secondary air injection, because air, more specifically oxygen, is injected into the exhaust manifold after startup. Vehicles start on a comparatively rich mixture to allow for smoother running conditions. However, this has a significant impact on exhaust gas emissions. A notable increase in hydrocarbon (HC) and carbon monoxide (CO) emissions are found under these rich start conditions. By injecting air into the exhaust manifold the CO and HC can be oxidized. This reaction increases the temperature within the exhaust and the exhaust gas after-treatment system i.e. catalytic converter can begin working earlier due to meeting its light-off temperature.
The system consists of an air pump, a one-way check valve, and associated pipework. The system operates for a predetermined time after startup. Normally this duration is three minutes, when cold.