Quote:
Originally Posted by KRAM36
The pump noise I hear is just like when you first start up the car. You will here a slight pump noise then it goes away. I'll pull up to a stop sign and hear that exact same noise. Not every time I stop, but occasionally I hear it.
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That is the secondary air injection (SAI) pump testing the integrity of the system. The SAI system is part of the emissions package so the ECU commands a test each time the car is started. This usually happens at the first red light or stop sign that you come to.
To execute the test, all of the SAI system valves are commanded closed and the SAI pump is commanded on for several seconds. The system measures the pressure increase thereby validating that the SAI pump is working and that the system does not have any pressure leaks. If the ECU does not receive the pressure increase signal, the ECU will set an SAI error code and illuminate the CEL on the dash.
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