Just today my S40 began making a knocking noise that was horrible. I checked the oil and it was low so I put in oil, checked all other fluids and they were at normal levels.
The sound went away so I drove home so I could look at it in the light in the morning first thing. The sound came back but not as bad.
I had it checked out the other day by a mechanic and he said it was right as rain since I had a light come on that I had to have turned off at the dealer since I don't have that key. But he never touched anything else on it and I was with him the whole time. So I am pretty perplexed.
I thought I would see if anyone else had the same issue or heard of it. Car does have miles on it but I bought it new and have always done the required maintenance as needed.