Toyota Tercel Trouble Codes

I Change The O2 Sensor But I An Still Getting The Code. Why Is That Could I Have Changed The Wrong One. I Changes The One On The Exaust.

I Was Driving My Tercel And The Engine Shut Off When The Check Engine Light Turned On. Almost Did It Again But Instead Ran Really Rough For...

Obd1 Code Readout Says Codes 31, And 41. Code 31 First. I Don't See A Mass Air Sensor On This Older Car Like My 2002 Tacoma. I Want To Try...