[FIXED] Audi A4 Weird Noise on Cold Start

***UPDATE: Turns out it was the secondary air injection (SAI) pump that was on the verge of dying. A simple part replacement corrects the problem. ***

My 2005 Audi A4 1.8T recently started making this weird yet loud whining noise on cold startups. The sound goes away once I start driving.

I've managed to isolate the area it's coming from (just below the headlight on passenger side) but have no clue what could be causing it, or whether I should be worried.

Any help is greatly appreciated! Thanks.

Category:

Autos & Vehicles

Tags:

• Audi
• A4
• Whining
• Humming
• Buzzing
• Noise
• Sound
• Whirring
• Problem
• Issue
• Cold
• Start
• Startup
• 1.8t
• B6

[blackttsupra320]

my friend used to have a vw jetta gli 1.8t, and he told me he brought it somewhere to get checked out and it was the heating of the catalytic converter. i have a 2003 audi a4 1.8t and mine does the same thing, every startup and goes away after 30 seconds...idk if this noise means there is a problem though?

[RickyTomatoes]

@blackttsupra320 I think I found the problem. Other people on YouTube have reported that the Secondary Air Injection pump is what makes that noise, typically indicating that it needs to be replaced.

[blackttsupra320]

@RickyTomatoes i have to look into that (secondary air injection pump). what the hell is that anyway? it's not a fuel injector your talking about right? i just purchased an 03 a4 1.8t with 140k on it, it's pretty clean and handles and drives nice, but yeah mine makes that injection noise you refer too on first cold startups. you have any idea how much it is to change the timing belt on them atleast price?

[RickyTomatoes]

@blackttsupra320 The SAI injects fresh air into the exhaust stream to allow for a fuller combustion of exhaust gases. It's basically used for emissions. If you unplug it, your car should be fine without it.

My A4 is at 99,500 KM right now and almost due for a timing belt change. Because of the amount of parts that need replacement, and all the man hours needed to finish the job, timing belt changes at a good shop can run you anywhere from $600 - $1000.

[otherhanwei]

holy crap. I have a 2005 A4 1.8T with 75k miles and my car has been making this noise for about 3 weeks now. It only happens on cold start ups and goes away after about 30 seconds when I start driving. I can't figure out what it is. And just this weekend my car started to overheat. Were you able to figure out what the sound is?

[VTSPQR]

It kind of sounds like the turbo, but it is really hard to hear in your video.