My PLX DM5 afr gauge is stuck at 14.5:1


My PLX DM5 afr gauge just became locked at 14.5:1. I'm guessing its the O2 sensor and I'm hoping that someone can tell me which one to get. I think the one that came with the gauge is made by Bosch but I don't know which one. I'm sure that there are many other Power Logger users that have PLX gauges and hopefully one of you sees this post. Thank you in advance.