I've posted this is the General Tech forum but think it hasn't been seen enough so I'm reposting it here. Don't worry I'll delete the old one ASAP.

Some questions about a 1998 Audi A4 1.8T FWD.

First, I had my car diagnosed and he found that my boost valve was not operating properly.
The fault code displayed is "04EE/BOOST VALVE OPEN(open) PRESSURE CONTROL".
Apparently it does not always activate on demand. He suggests that I replace it.

Second, the indicator under the speedometer flashes "OIL" everytime I start the car.
I changed my oil 5,000 kilometers ago so I find it strange that the light has turned on despite the fact that the oil is supposed to be replaced every 10,000 kms. I was told that the Oil Level sensor also needs to be replaced.

Third, when I left my car parked in 30degree celsius heat and came back after several hours, the car started weakly and idled below 1,000 rpm and promptly died. This happened 2 more times until i floored the gas upon starting to keep the engine alive. I changed my spark plugs, battery and oil 4 months ago. Why is this happening?

Finally, my key reader does not always recognize my key when I start the car.
The error code displayed is "463A-ENGINE CONTROL UNIT DISABLED/ALARM".
The immobilizer light flashes when i insert the key. What could be causing this problem?

Any advice on the following matters is greatly appreciated.

 

sounds like you already have the solutions, not much to respond to. I cleaned my oil level sensor and it works great. The 3rd sound like you may have gotten a faulty battery, which would pull on the alternator,maybe slowing your idle.
key ,maybe get reprogrammed. sorry