engine light is on

I bought a used car yesterday. The engine light is on. there was almost no oil when I checked the car. I thougth it caused by that. So I added 10w30 oil after I bought the car. Now the light is still on. what is the problem?
the car is 2000 honda civic, 175K, auto
thanks,

所有跟帖： 

• seller said this light is on since begining of this year. -majorindulgence- ♀ (21 bytes) () 04/15/2010 postreply 07:03:19

• It could be many things. -iammadaboutu- ♂ (457 bytes) () 04/15/2010 postreply 07:06:10

• go after who? used car is sold as is. -用户名被占用了- ♂ (0 bytes) () 04/15/2010 postreply 07:21:24

• You are right. I am not sure if he can. -iammadaboutu- ♂ (289 bytes) () 04/15/2010 postreply 07:34:05

• ok, i will do that. -majorindulgence- ♀ (0 bytes) () 04/15/2010 postreply 07:35:08

• thanks, the I saw the light on before I bought it. -majorindulgence- ♀ (24 bytes) () 04/15/2010 postreply 07:34:26

• 500 dollar, or even less? -用户名被占用了- ♂ (0 bytes) () 04/15/2010 postreply 07:48:02

• You can read out the code and google. -jin_yin_hua- ♂ (0 bytes) () 04/15/2010 postreply 08:31:01

• 你这车怕有大毛病 -biglow- ♂ (165 bytes) () 04/15/2010 postreply 08:51:09

• I will check code this evening -majorindulgence- ♀ (336 bytes) () 04/15/2010 postreply 09:05:23

• the code is P0135. they also point out which wire I should chang -majorindulgence- ♀ (0 bytes) () 04/16/2010 postreply 13:00:54