Well,

My 1990 D-150 (318 Automatic, throttle body) was running so good. Today on the way home it started running rough again at a stop light.

My engine check light came on. I got my scan tool out and it showed code 052 excessive lean.

any idea's on what is causing this one?

Thanks

Gary

 

Haynes manual give that code will turn up when signal from the O2 sensor isn't right. I will check that out tomorrow and go from there.

 

I'm Going to guess a wiring problem? Code 052? O2 is normally a Code 21??
But I think you need a DRB-II to reset the Emission Maintenance Reminder ...
Rest of the tune up is good? Cap, plugs, rotor, plug wires, and so on.