Allison Transmission Questions Hi there Ken Powell, Yes it should be done by authorized Allison mechanic because the whole valve body module needs removal to replace the temp sensor or repair the wiring that may have rubbed thru the insulation. If it were as simple as not warmed up, there would be a flash of OL70 on your display. I hope you still have warranty. This takes approx 4-5 hours to do but the parts are not that bad. If I can help any more, please call me at 360 887-7556 my direct line at Pacific Detroint Diesel Allison. Thanks and have a great day!