Code 41: Hego Senor

[raceman]

I have a 1991 Ranger with 4.0 and a couple months ago my truck started acting up for about half the day (chugging, sputtering,idleing rough) an it cleared up then about 1 week ago it started doing it again and my fuel pump went out so I replaced that thinking it was going to solve all problems an still runs like sh**. Took it in today an diagnosed it an it came up code 41 Hego sensor lean exhaust bank 1. Can anybody tell me how I might be able to fix this? I was told it also that it could be vacum issue or fuel pressure issue or MAP sensor. If anybody has any ideas they would be greatly appreciated, its kinda hard not haveing a vehicle.
Thanks

 

[mikeinri]

Welcome!

I haven't had that one yet, sorry.

Depending on how much success you have here tonight, you may want to bring it to another shop, one that will do a full diagnosis, not just spit out the code that you could have done yourself with a paper clip.

Another alternative is to go to Autozone and give them your code. They should be able to print a full diagnostic on a cash register receipt (for free). These will inlcude full electrical diagnostic procedures (how much voltage on what color wire, etc.).

Hope this helps.

Mike

 

[MrShorty]

Lean O2 sensor codes can be among the most difficult to diagnose, because there are so many possibilities (though I wouldn't expect it to be a MAP sensor in this application because a '91 4.0 didn't use a MAP sensor to my knowledge).

Was the 41 a CM code only, or did it show up in the KOER test as well (can indicate if fault is intermittent or not).

"By the book" the usual first test with an O2 sensor code would be to check fuel pressure.

Does the engine seem to be running lean as indicated by the sensor, or is it running rich?

 

[raceman]

No we ran a koeo test on it an thats what came up and we cleared the code an I went out an drove around till the check engine light came back on an we ran another koeo test an it threw out the same code but we did run a koer test an it threw out code 42 which is it is running rich but we ran the koeo test multiple times an it always came out to be lean. My truck runs like it is running lean ( chugging, sputtering rough idle as if its not getting enough gas) but when driving you can smell gas fumes (have a couple manifold leaks) as if its putting in way to much fuel an not enough oxygen an it is running rich. But with the truck starting cold it runs almost perfect as always till it warms up then thats when the problems start an it gets worse the longer you drive it.

They printed out a pinpoint test an its a bunch of steps you go through till you figure the problem out and it shows what could be the possible causes and I dont have the paper with me right now but I know some of them were pcv valve wich I replaced after we did the test an it did nothing and some of the others were map sensor, thermactor, vacum, and there were about 5-6 other things.

 

[MrShorty]

Where it seems to be running rich and the O2 sensor indicates lean, I'd look at the O2 sensor circuit.

 

[Robrt32]

I had similar problems and took my MAF out and cleaned it with electrical cleaner and fixed it right up.... Unplug the MAF, drive it and see if it runs better.. Mine DID, so i knew that could to be the culprit... worked out for me.... I went through that BEFORE i discovered this board..