Ye olde PCI bus. There is no actual 'code' generated for this issue and is why you see the no bus message on the cluster. The sensor goes out and 'brings down the bus'. I've done enough of them over the years to know.
Pretty sure they're on the right side in an older Ram. Sensor is $55-75 depending where you get one. Its a 15 minute job with a lift, the right extensions and swivel sockets. Otherwise, it can be a *****.
I've had to do it twice in my '01 Cherokee, neither time in a shop - once in my driveway and the other parked in front of a friends house. In my car it's on the left side. You can reach it from the top but its hard to do, much easier from the bottom.