My trans is in limp mode what sensor can make that happen.....? on 2007 Chevrolet Impala

The only code its reading is for the upstream o2sensor....

Asked by for the 2007 Chevrolet Impala
Perhaps you need a differant scanner to get the transmission fault codes. Not likely that a o2 sensor would put transmission in a limp mode.
what will make that happen... Cause da check engine light is off now and no codes r showing..