Now that I'm a member of the forum.. I have a question.

[AKFox]

I used to play gran turismo 4 all day long. But I got tired of it and sold it. I just got it back but I can't get it to run on my slimline PS2. I always wanted to know how can i fix it? I get a disk read error when i pop it in.

 

[Ryou]

This happens in my slim too, I don't know why. I think it's the lens, you may have to clean it.

 

[BH-21]

Before I tried cleaning the lens in a PS2 and possibly ruining it forever. I would try cleaning the disk itself by hand. Using room temperature not cold or hot tap water. Rubbing with my thumb in the water stream from the middle out to the rim. Then when you think you have gotten it scrubbed dry with a soft towl or cloth from the center out to the rim like you did with your thumb. The towl had better not have soap residue or anything else in it or your wasting your time.

 

[Parnelli Bone]

Gotta be one of two things: either the disc itself is at fault, or the PS2's laser lens is dirty. If cleaning the disc and laser doesn't help (and it's a used or old copy of GT4) you could try buying a brand new copy of GT4, which doesn't cost much these days. That's what helped me long ago when I got the red circle of death.