2004 Tacoma ABS flashing

I recently bought a 2004 4x4 tacoma from a chevy dealer and with in a month of driving it the clutch went out. Luckily they replaced the clutch free of charge but when i picked my truck up I noticed two things. the ABS light was flashing and the service engine light was on. upon getting home i plug my OBD2 reader in to find out the check engine code,p0031, and it says O2 sensor #1 is acting up. ok np i can deal with lower mpg. I don't like the abs light flashing at me and idk why my check engine light and abs light showed after having the clutch worked on. any ideas and how to fix it? I thought it might be low brake fluid but its been snowing all day and i didnt want to mess with opening any of my engine bays fluid containers and risk letting snow in them, plus my house is on a hill with no level surface so there's that too.

Please note my skills in DIY fixing for vehicle is novice at best. I mean i can do basic maintenance repairs but anything more and i'm not sure what im doing.

 

Update. I disconeccted my Fixd obd2 reader and the abs stopped flashing so i just have the p0031 check engine code to deal with and if it went out it looks like a easy install. Im thinking that the cable wasn't put back in fully and thats what's causing my o2 sensor to pop errors?