I have a 94 F-150 5.0L 2wd automatic with 185k miles, over the past 18 months it has started going through oxygen sensors every 2,500 miles or so. Has anyone seen a good technical description of this system for troubleshoting and/or any input if you think it will help.

To answer some questions in advance. When the sensors die they read nothing on a meter. As soon as I replace it runs fine. This entire thing started when I drove through a big puddle in a desert monsoon and the check engine light came on. I took it to a mech who put it on the tester and said it was showing the code for running lean. Changed injectors and intake manifold gaskets. Ran much better but still had check engine light cycling on and off. That's when I changed the first O2 sensor. Since then it runs fine for 2,500 miles then the check engine light comes on which leads to new sensor. I do have a significant oil leak that gets the O2 sensor wiring harness and connector wet. I have tried sealing it but still burned up the sensor at 2,500m. I have also changed the wiring harness from the battery/starter/solenoid as it contains the harness for the O2 sensor.

That's all I can think of for now. Any help is appreciated

 

Greetings,
You say that you drove through a monsoon. Check your 60 pin connector to your processor. Had a problem with my 95 that drove me nuts for a month. Found corrosion on the "signal return" pin, and the "O2 sensor signal" pin. Signal would drop out (indicate lean) and the processor then dumped so much fuel that the engine wouldn't run. Cleaned the contacts between the connector and processor and all was well. Also found that the gasket to the processor was loose, and was allowing moisture to get into that little well that holds the processor. Remember that the signal from the O2 sensor is very small, so any hiccups in the wire to the processor will wreak havoc on the system.

Hope this helps,

Tim

 

Thanks, I'll check it out.