In the VVT (Variable Valve Timing) system, the appropriate intake valve open and close timing is controlled by the ECM. The ECM performs intake valve control by performing the following: 1) controlling the camshaft and camshaft timing oil control valve, and operating the camshaft timing gear; and 2) changing the relative positions of the camshaft and crankshaft.

To reduce HC emissions, evaporated fuel from the fuel tank is routed through a charcoal canister to the intake manifold for combustion in the cylinders.

The ECM changes the duty signal sent to the purge VSV so that the intake amount of HC emissions is appropriate for driving conditions (engine load, engine speed, vehicle speed, etc.) after the engine is warmed up.

The ECM uses sensors mounted in front of and behind the front catalyst to monitor its efficiency.

The first sensor, the air fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, sends post-catalyst information to the ECM.

Refer to DTC P0412 ().

Refer to DTC P0013 ().

The ECM operates the air injection VSV relay (AI-VSV) which causes the No. 2 emission control valve to operate.

These DTCs are designed to detect opens or shorts in the camshaft timing oil control valve circuit. If the duty-cycle for the camshaft timing oil control valve is excessively high or low while the engine is running, the ECM will illuminate the MIL and store the DTC.

The secondary air injection system injects air into the exhaust port of the cylinder head using an electric air pump, starting when the engine is started cold and operating until the catalyst warms up, in order to promote combustion of unburned fuel and decrease the amount of hydrocarbons (HC) and carbon monoxide (CO) in the exhaust gas.

Refer to DTC P0010 ().

The exhaust camshaft's Variable Valve Timing (VVT) sensor (EV1, EV2 signal) consists of a magnet and MRE (Magnetoresistive Element).

The exhaust camshaft has 3 teeth on its outer circumference.