Tech notesStart by inspecting the transmission fluid level and condition, and change fluid if necessary.
There is a factory service bulletin fo the following Chevrolet models:
Chevrolet Factory Service Bulletin OBDII Code P0730
When is the code detected?The TCM has detected that the transmission is trying to mechanically shift to a lower gear than intended
P0730 Chevrolet DescriptionThis diagnosis monitors actual gear position by checking the torque converter slip ratio calculated by Transmission Control Module (TCM) as follows:
Torque converter slip ratio = A x C/B
A: Output shaft revolution signal from speed sensor (revolution sensor)
B: Engine speed signal from Engine Control Module (ECM)
C: Gear ratio determined as gear position which TCM supposes
If the actual gear position is higher than the position supposed by TCM, the slip ratio will be more than normal. In case the ratio exceeds the specified value, TCM judges this diagnosis malfunction.