rockblock

Folks,

I have a 1999 A4/2.8 Quattro...yesterday, I noticed a weird "fan" type of noise coming from the passenger side near the radiator (none of the 2 big radiator fans) after I shut down the engine...after 4-5 minutes, the noise dissappeared, but after another 4-5 mins it came back on...I'm not sure where or what exactly generates that, but I hear it and I can feel a draft right next to radiator. What's weird is that it goes on & off every 5 mins, even with my engine off...last night it drained my battery and I had to recharge...the only way to stop this on/of noise is to disconnect the battery...

After I charged the battery, I ran ODB2 diagnostics and no fault code came up. When I ran VAGCOM, I got the following fault code:

Address 01: Engine
1 Fault Found:
18010 - Power Supply Terminal 30: Voltage too Low
P1602 - 35-10 - - - Intermittent
Readiness: 0000 0101

After a reset, no further codes appeared, yet the fan keeps going on/off every 5 mins...any clues what it could be?

Thx

4Driver4

Is it the aux coolant pump?

rockblock

I don't know, where is that located? I can only see 2 big fans behind the radiator: one right behind it and one to the left of the radiator....none of them are spinning when this noise happens, yet there is a faint draft coming from somewhere...are there any other fans other than these 2? also, the fan noise sounds a bit "metallic" as opposed to a regular fan

4Driver4

Coolant pump is beside and behind the alternator.

anarchyjet

Search secondary air injection or SAI

audiman09

i had the same problem. it turned out it was the airbox relay. its what sucks in the air when you start the car. the relay was bad in mine, took it to my mechanic and fixed it. havnt had any problems since.