p2121 p2127
 

2006 cummins 2500 with edge programmer. I am throwing the error codes p2121 and p2127. I have replaced the apps sensor but am still throwing the codes. I no that reflashing the main computer will not fix my problem. I have been told that i would need to replace the main computer if I want the error codes to stop coming up. The reason I dont think it is the computer is because im only getting these error codes when it is either a moist day, raining, or snowing leading me to believe that it is a bad connection in one of the wire harness that is causeing the voltage reading to be incorrect. I have recently read that it could be the connector on the top of the cp3 pump. I have had it appart before and it didnt solve the problem. I am going to check it again but i am wondering if there is another connection somwhere in the wiring harness that i could check that would be causeing these error codes to only come up depending on the weather. If the weather is shitty, the p2121 will come up as soon as i start the truck, after driving it for about 2-5 minutes p2127 will come up. I can clear the codes out of the computer but they will continue to come up untill the weather clears up. Any Ideas?

sounds like a bad connection to me

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clean them and use some dielectric grease on them

Remove the Edge and see if the codes come back.

i removed the edge and it didnt change the problem. its gotta be in one of the connections just trying to figure out where to start

With the connection on the APPS still plugged in, remove the sensor and inspect the connection and the wires. If they look normal, unglug and clean the connection as mentioned above. If that still don't work, the harness is damaged further up, got an ECM issue, or the APPS is bad. Did you install a used one, or was it new??

Updates??

Please update.

the connection from the wiring harness to the fuel water seperator was dirty. cleaned the connection and filled it with dielectric grease. havent had any problems with the codes coming up since then. its odd that that connection was causing the codes to come up because i have never heard of that being an issue, but i guess its all tied togeather in the harness and that was what was causing the problem.

If there is a slight difference in voltage, it'll set a code.

Problem sounds fixed, so I will close the thread. If it should come back, you can reopen the thread.