So I finally got my truck running and everything working the way its supposed to but my check engine light is on. I just replaced the oxygen sensor and my truck runs better than it did but the check light is still on. It goes off at WOT then it comes back on every time any ideas here ?

 

You're going to have to pull codes to know whats setting it off

 

My mechanic says my trucks computer wont communicate with his scanner all I know is that it shuts off when at WOT then comes back on when I let of the gas

 

Check your fuse panel, the fuse that powers you're cigar lighter also powers the communication port. Also what year is your truck?

 

Its an 89 lariat 4x4

 

You can either purchase a OBDI reader or read up on how to retrieve the codes yourself

https://www.f150forum.com/f10/how-re...es-obdi-10907/

 

Think about that for a second.

Then I would start wondering why you replaced an O2 sensor, if your codes don't read out.

Then learn the paper clip method of reading your codes before you delve into "communication problems" with your ECU. Verify for yourself whether or not it is recording or transmitting codes.

Next, I would verify that every single vacuum line is pulling as it should.

Until you get a baseline, its hard to know where to go. If its your ECU.... well, that sucks. But honestly, thats pretty rare compared to the 16 million CELs that pop up every day.

#1 - is usually a vac line.

#2 - on older trucks its a broken or fouled/dirty/gummed up electrical connection.

#3 - recheck 1 and 2

#4 - get your multimeter and start verifying sensor conditions.

#5 - go back to 1 and 2.

Post up when you know what your codes are and you have full vacuum in all lines.

Good luck.

 

Well my o2 sensor was broke in half at the porcelain that's why I changed that. and my truck will not throw codes to an obd reader that's why its a shot in the dark. The computer wont throw any codes as if its dead so I don't know