Some of the most common Allison transmission codes include 22 for issues with engine and turbine speed sensors, 14 for issues with oil level sensors, and 65 when the engine rating is too high. The number 13 is the main code indicating a problem with ECU input voltage of the battery. The number 24 is the main code for situations when the machine overheats and the sump oil temperature gets too hot.
Allison transmission codes indicating issues with oil level include "L 0X" when setting time is too short, L 50 when the engine RPM is too low, and "L 59" when the RPM is too high. Seeing 61 means that the retarder oil temperature is too hot, so there could be an issue with the retarder apply system or the current amount of fluid cooler.
A display of 22 is the main code for problems with engine and turbine speed sensors. The main code can be followed by subcodes such as 14, for engine; 15, for turbine; and 16, for output sensors. The number 12 is the main code indicating issues with oil level, which is followed by either 12, when oil level is too low, or 23, when oil level is too high. "L Ok" shows that fluid level is correct.