CEL comes and goes on my 99

I have a 1999 2.5 boxster, and ever so often my CEL comes on, and then goes away after a day or so. Sometimes I will go several hundred miles, and then it comes back. WTF

R

[Tool Pants]

When the car computer senses a fault in the emission system the warning light comes on. After a number of drive cycles if the fault is not detected again then the computer turns the light off.

There are a 100 reasons for the light to come on. You need to have the falt code(s) read out to determine why the light is on.

Went to autozone and this is what they came up with. 3 different codes, here they are

P1121
P0446
P0160

They cannot determine exactly what they mean, but can you guys?

Thanks in advance.

Rich

[Tool Pants]

At the top of the screen click on DIY Menue. http://www.renntech.org/forums/index.php?autocom=downloads&showcat=37

The OBD II fault codes are listed according to the year of the vehicle.