2000 A6 wagon,
Normally starts right up now off and on I have to turn key it turns over for about 5-6 seconds and starts sometime I have to try to start it again and then it will start.

 

I replaced an ignition switch on my 04 allroad last year. Solved my problem.

But now I am having a similar issue and it isn't the ignition switch so I am faced with diagnosing this problem myself.

 

i think u replace ur engine or and try to keep monthly maintenance and service

 

Just had same issues. Finally it just wouldn't start and The engine light came on. Ended up being cranshaft position sensor and camshaft position sensor. You may wanna check your coolant temp sensor as well. Seriously.

 

I replaced an ignition switch on my 04 allroad last year. Solved my problem.