Chevrolet Astro Computer Read Codes

I Am Getting Two Codes P.0155 And P.0059 Related To Oxigen Sensor Do I Neet To Replace It? How Can I Check The Oxigen Sensor?

The Mechanic Check The Car With A Scanner, He Told Me That The Computer Does Not Work Properly. I Am Electronic Egineer, May Be I Can Repair...

I Was Told I Could Jump Out Two Terminals And Get The Code By Counting The Flashes On The Service Engine Light, What Two Terminals Do I Jump...

I Have A 94 Astro Van I Had It In The Shop And He Said It Had 2 Codes I Am Trying To Find Out What They Are And How Hard It Is To Fix Them...