2003 Audi A4 winning noise when engine is cold

VICTORRAND

MEMBER
2003 AUDI A4
4 CYL
AWD
AUTOMATIC
68,000 MILES

Winning noise from under the hood passenger side toward the front of engine compartment for about 2 minutes after starting cold engine. After about 2 minutes noise goes away

Saturday, August 8th, 2009 AT 9:54 AM

3 Replies

DUBTECH

MECHANIC
159 POSTS

That is your Secondary Air Injection pump. It is part of the Emissions system and is normal for it to run on start up.
As long as the MIL is not on in the dash it is operating properly.

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Sunday, August 9th, 2009 AT 5:03 PM

VICTORRAND

MEMBER
2 POSTS

Thank you Dubtech. I purchased this car new in 2003 and until recently I could hear it slightly. Which must be normal. However, it is now much louder than it used to be. I can hear it when my wife drives away for about 300 feet. After about 2 minutes or so, it stops completely and we will not hear it again until we start a cold engine. Do you think something could be clogged?

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Tuesday, August 11th, 2009 AT 7:19 AM

DUBTECH

MECHANIC
159 POSTS

It is an air pump and the pitch will change based on the restriction of airflow. Sometimes the "Kombi" valve doesn't open, which then strains the pump because it is trying to push air into a closed valve. The air pump itself sometimes warps and leaks through the seams of the assembly. Both are common problems, but the ECU can and will detect any loss of flow. Since it is part of the emission system it is tightly monitored and should turn on the MIL if there was a problem.

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Tuesday, August 11th, 2009 AT 10:14 AM