How can a computer have a memory problem and why would this occur? I was going over a mountain pass when the check engine light came on for this. The next day the light was off. Went back over the pass and it came back on. Then the tranny sounded and felt like there was an issue. The next day the light went off and it was fine again. Local dealer said there was an internal fault with the Tranny module and it has a memory error so I must replace the TCM.