For best efficiency the upstream catalytic converters first have to reach an effective operating temperature during warm up and for this reason an air injection system is installed in the 2005 and later models of V8 cars. The components include the PCM, the CIAICD, the electric air pump, the air pressure sensor, the EASV, two VSVs and two worth of vacuum type air switching valves and corresponding plumbing and wiring harnesses. The PCM employing the information from the ECT and IAT sensors to determine the engine temperature and estimating the right amount of air needed to warm up the catalysts in case the engine is cold. When triggered, the PCM makes the VSVs turn on, AI control driver, the air pump and electric air switching valve and lets air into the exhaust manifolds which assists in burning the unburned fuel vapor residues and at the same time the heating of the exhaust gases and upstream catalysts. The air injection system is considered reasonably robust and few failures occur, however where a failure has occurred then component replacement/renovation could be required, and some of these component may require intake manifold removal to access. Air injection control driver is to the left of the engine compartment sill while the VSVs are on the right side of intake manifold. As it can be observed, the vacuum-type air switching valves are found at the back of the engine and they are attached to the rear coolant bypass housing. Concerning the air pressure sensor, electric air switching valve, the air pump the intake manifold must to be unplugged. Each of them can be disconnected and separated; installation means the reverse of removal; if some gaskets were replaced, it is necessary to use new ones. If replacing the air pump, the air pressure sensor and the air switching valve can be incorporated in a single module that can be easily serviced.