Originally Posted by
Mr5150
Is it normal for the air pump to come on while at a red light or stop sign? I know its supposed to come on on cold starts and then shut off but occasionally I hear a vacuum cleaner under the hood. It stays on for less than 5 seconds.
Could this be the relay needing to be replaced?
The system is tested first time you stop after your car has warmed up. If you hit the gas before the test is finished it turns off the pump and tries again later.