Ok, so I was able to help my girlfriend get a nice 02 passat last week and I'm trying to fix the problems.
First the heater wouldn't work, but I was able to change the cabin filter and flush the heater core.

Then I noticed some of the common vacuum lines were bad and I was able to change them, but now onto the codes.

There have been 4 codes since she got the car.
17887/ P1479/005241 - Brake Boost Vacuum System: Mechanical Failure
I have been able to log this problem and I'm able to see when I hit the brake it says operate and when I pump the brakes a lot the pump come on and I can here the relay with the hood popped, but I still can't find the problem. Could it be the relay and where is it?

19534/P3078/012408 - Throttle Control: Airflow at Idle too Low
I have looked at all the lines that I can see that would be bad and changed them, but still can't find the problem. Could it be the n80 and where is it on this car, under the intake manifold or on the inlet pipe?

16840/P0456/001110 - EVAP System: Very Small Leak Detected
I can't find leaks and I guess it can be a gas cap, but not for sure

16795/P0411/001041 - Secondary Air Injection System: Incorrect Flow Detected
I was able to lay under the car and here what I thought was the pump kicking on, so I don't know if its just a relay or what?

The other problem I have seen is when she takes the key out and the headlights are still on, it doesn't make the warning sound and when you open the drivers door the interior light only come on for a split second.

Please help me as much as you can.
Thank you in advance

 

suggest clearing all the active codes. then see what, if anything comes back.

not sure about the headlight, driver's door thing. sounds like a bad switch somewhere.

good luck

have fun

 

Have cleared them a few times, but they still come back.
I found a 20A fuse in the fuel pump location, but it calls for a 15A fuse.
That bad?

 

P0456- Check the part number on the fuel cap. the updated one ends with a G. replacing it with an updated cap will most likely fix your EVAP code.

P0411- SAI pump is a relatively common problem. if you don't need the car to pass emissions, just ignore it. you will still get the CEL though. you can have it programmed out if you get the car chipped. otherwise, check the pump, hoses, N112 valve, and the relay.

P1479- if the pump is running, and the fuse doesn't blow, the problem is most likely in the vac line

not sure about the throttle control code

-not an expert, just an enthusiast