Well, this one is a new one on me. I threw a code 242 and it is tampering with the speed sensor. IT is for trucks where they govern the speed. It went off on me and I was derated down to 2000 RPMs. It did not make a huge difference and I stopped at Jacksonville Cummins and they deleted it from the ECM so it will not happen again. Oh they did say that be careful of any fuel upgrades. Many times they hide EPA stuff in there and you will get lower horsepower and lower milage and less power.
John, What is a fuel upgrade? As in premium? Or a code a wrench would put into the computer? How would one know that is what they are purchasing? Thanks, David
The fuel upgrade was for the fuel delivery. It was a new one but had EPA stuff mostly.
I recalled talk about CEL code of 242 before....
CUMMINS PID 84 10 ? (http://www.foreforums.com/index.php?topic=12860.msg68690#msg68690)
Silver Leaf Diagnostic Code Question (http://www.foreforums.com/index.php?topic=12398.0)
If 242 with PID of 84 10 you may be looking at the output speed sensor on the Allison
http://ww2.justanswer.com/uploads/JCTech012/2009-11-13_110804_FC242.pdf (http://ww2.justanswer.com/uploads/JCTech012/2009-11-13_110804_FC242.pdf)
YEs it had a couple numbers after it saying tampering with the speed sensor. There are three of them under there and it said a warm start will fix it too. But the why is the reason I went there. Must be mid harness as it threw the code at 1358 rpms.
John,
Noticed this is not a new item for you, you had similar issue while in the Moscow Iowa, HWH area in 2011. Just a thought, a on going ??
Dave M
yes I had a leaking main seal that I had allison change out last winter. It leaked and gave me the code on speed sensor. Now the sensor was clear and clean and working but it gave me the coade I was trying to disable the governor. I understand that lots of trucking companies limit the max RPMs in top gears to prevent trucks form going to fast and using too much fuel. This was my issue and it thought I was trying to override that.