Secondary Air Injection (SAI) Pump

Secondary Air Injection (SAI) Pump





The SAI pump is attached to a bracket at the rear RH side of the engine compartment and is fixed to the bracket by three studs and nuts. The pump is electrically powered from a 12V battery supply via a dedicated relay and supplies approximately 35kg/hr of air when the vehicle is at idle in Neutral/Park on a start from 20 degrees C (68 degrees F).

Air is drawn into the pump through vents in its front cover and is then passed through a foam filter to remove particulates before air injection. The air is delivered to the exhaust manifold on each side of the engine through a combination of plastic and metal pipes.

The air delivery pipe is a flexible plastic type, and is connected to the air pump outlet via a plastic quick-fit connector. The other end of the flexible plastic pipe connects to the fixed metal pipework via a short rubber hose. The part of the flexible plastic pipe which is most vulnerable to engine generated heat is protected by heat reflective sleeving. The metal delivery pipe has a fabricated T-piece included where the pressurised air is split for delivery to each exhaust manifold via the SAI control valves.

The pipes from the T-piece to each of the SAI control valves are approximately the same length, so that the pressure and mass of the air delivered to each bank will be equal. The ends of the pipes are connected to the inlet port of each SAI control valve through short rubber hose connections.

The T-piece is mounted at the rear of the engine (by the ignition coils) and features a welded mounting bracket which is fixed to the engine by two studs and nuts.

The foam filter in the air intake of the SAI pump provides noise reduction and protects the pump from damage due to particulate contamination. In addition, the pump is fitted on rubber mountings to help prevent noise which is generated by pump operation from being transmitted through the vehicle body into the passenger compartment.

If the secondary air injection pump malfunctions, the following fault codes may be stored in the ECM diagnostic memory, which can be retrieved using 'Testbook':

P-code Description
P0418 Secondary air injection pump powerstage fault (e.g. - SAI pump relay fault / SAI pump or relay not connected / open circuit / harness damage).