89 Ranger 4cly.

Which one is right, Chilton or FTE. Here on the forums,https://www.ford-trucks.com/lc/lc.ph...jection.com%2F it says Code 48 is "Loss of IDM, left side." In my Chilton manual, it says it is a bad Oxygen Sensor.

I replaced both, and still get the error. Also replaced the plugs and wires. All parts are new. I have checked and cleaned all the connections as well. I cleared the Long and Short term memory, and it instantly comes back.