So here's the story:

My 1995 P38 4.0 threw a P0138 code and I kept driving it normally. Worked fine until I'm exiting the highway and the truck stalls, saying gearbox fault, tcs fail, etc. I get the car started after about 20 minutes and limp home.

I research, narrow the issue down to the crankshaft position sensor, order part ADU7342L and replace. Truck starts.

Only problem is that the truck is misfiring, and at mid throttle it stumbles a bit before regaining power. I read the codes again, and it's showing three:

P0138
P1316
P1775

Any ideas on what's going on? I'm at a loss.

 

P0138 (oxygen sensor high voltage)
P1316 (misfire due to high emissions)
P1775 (gear box fault)

With the gear box fault and traction control messages, it leads me to believe it is actually the becm acting up. Have you noticed any other unusual behavior, such as battery drain alarm issues etc? When does the problem happen? Continuously or when it warms up? It could be a number of things, but more information will help us give you a more definitive answer.

 

How many miles are on it? How long have you had it? Has it ever done this before? When was your last basic tune up? I have always found it is much easier to diagnose a problem such as this when you are positive that all of the basic stuff(plugs, wires, fuel filter, etc) is 100%. Also, are your battery posts nice and tight and corrosion free? Hope that gives you some ideas.

 

No, I haven't been having any other issues. Just changed the battery, actually. No alarm issues.

The misfiring at idle has stopped, but the car continues to 'stumble' at about 2000 RPM when I'm at 1/4 to 1/2 throttle on the gas pedal.

 

113K Miles. I've had it for about 2 years. Spark plugs were changed when I got the truck, but I did not change the wires. Battery posts are nice and tight, as it is a new battery, and corrosion free.

 

Time for new plugs then . I would also replace the leads.

Now that you mention that you replaced the battery, did it only display traction and gear box fault once? Mine will do this after I reconnect the battery, and turn it on, but only once. Are you positive you replaced it with the correct battery?

 

The gearbox fault and traction messages do not read on the display. At this point, it's just the trouble codes.

The misfiring seems to have stopped at idle. The truck is only stumbling while driving now.

I got a direct replacement for the old Bosch battery, so I know it's ok.

 

I still say its the plugs or leads... Even if they are not the problem, it is time to change them anyways.

 

EVERYTHING FIXED!

Turns out the sensor was installed improperly. I put the washers on the wrong side of the sensor (the outside), and it caused the moving parts in the bell housing to get caught up on the sensor probe.

Ordered another sensor, installed the washers on the inside of the sensor, cleared the fault codes, and everything is hunky dory!

Thanks for all the suggestions!