Operation

OPERATION

The electric air pump only functions during cold starts. The PCM will not command the electric air pump to run if the engine coolant temperature is 10° Celsius (18° Fahrenheit) above ambient temperature or if the engine coolant temperature is above 37° Celsius (98.6° Fahrenheit). The air pump will not run more than 20 seconds during this cold start condition. The air inlet tube to the electric air pump is equipped with a mass air flow (MAF) sensor. This MAF sensor monitors air flow to the exhaust system and is used to diagnose the system by making sure the correct amount of air, not too much or too little, reaches the exhaust system. Each component of the secondary air system is diagnosed assuming the other part is functioning correctly. The diagnostic tool can command the air pump ON with the key ON and engine OFF (KOEO).