P2121 ??

[JHumphries]

As I was leaving work tonight, I accelerated, somewhat briskly , to get on the highway. I don't know what rpm, but the truck lost power, dinged and gave a check engine light. The moment this happened, I let off of the throttle and disengaged the clutch. I looked at all of the gauges, and display, and everything was normal. I eased the truck back into gear and got on the highway. I drove the next 10 miles home without incident.
When I got home, I downloaded the code: P2121
I searched the forum for "P2121", and found very little information similar to my situation.
It initially felt like the clutch had slipped, but I had no other indications. I didn't notice if the engine had reved.
2006 manual.

 

[befrazier]

I had the same code on my truck two times now. I replaced the APPS sensor under the drivers side battery box and the problem did not go away. How I fixed it the first time and the second time is I unplugged the APPS sensor and cleaned both male and female plugs with electronic cleaner spray. Let it dry good and applied di-electric grease to both fittings. Put it back together and all is good. It would be worth a try before you spend the money on a new sensor like I did the first time and it did not even help. Not sure if your sensor is in the same place as mine since our models are different. But if so, the easiest way to it, is to drop the drivers side fender well and there it is, right under the battery box. This is the easiest way to get to it on the 04. 5. Maybe this will help. Good luck.

 

[6speed]

P2121 and P2122 are both related to the APPS

 

[befrazier]

I talked to timmbo apps guy and he made me a new pigtail plug that plugs into the apps sensor under the battery box. I had a guy take the old plug off and install the new plug. He noticed on the old plug that there were two pins loose inside of it. The truck runs great now. Any of the trucks that have the apps under the battery and is having the reoccurring codes may need to check this out. I have had this issue for several years and have bought two sensors with the same problem coming back. I had the guy check out the older apps sensors and they both worked fine. Hopefully this long process, trial and error, determination and the help from TDR and timmbo apps my problems are gone.

 

[JSooter]

Great info!
I really like all of the easy access to problems & solutions here on TDR. What a great resource.

Last night we just left home pulling the travel trailer and lost power, check engine light, etc. I'm seeing codes P2121 and P2123. I'll be checking the electrical connection before I spend $ for a sensor that I may not need.

Thanks!

 

[befrazier]

The APPS problem came back a couple of months after the pigtail replacement. Although I needed to replace the pigtail anyhow. I unplugged the two big electric plugs attached to the firewall on the drivers side, cleaned with electronic cleaner and put dielectric grease on every small pin hole and plugged back in. I was reluctant to post for quite some time after I did this because of the past failures. I have not had any problems for approximately 9 to 10 months now. Hope this may help someone.