I would not think that a error code for the ATF temp sensor would cause limp home mode. I do know that the ATF temp data is used when the TCM is formulating shifting strategies but I don't think it would be so important as to cause limp home mode.

When I use SDS to monitor ATF temps the data is always reported in celsius, was the snap on scan tool reporting 212F? In the 722.6 the ATF temp sensor is wired in series with the P,N reed contact switch. For the TCM to get ATF temp info the car must be in "D" or "R", if the car is in neutral or park the TCM will not receive ATF temp data and I believe it defaults the ATF temp to whatever the engine temp.

In looking at my Intro to the 722.6 manual there is a table that shows DTC's that will cause limp-home mode and the ATF temp error indicates that it would not cause limp-home mode but then references footnote "C". Footnote "C" states "with implausible signal input, control module defaults to a variable substitution value (with loss of one rear speed sensor input)"

It's not really clear to me why the loss of ATF temp data would result in losing data about the rear speed sensor situation but if true I could certainly see the lose of a rear speed sensor immediately causing limp-home mode.

I'd go back and see what codes show up in the TCM.

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