"Err" message on display
Whenever UltraGauge does not receive a response back from the vehicle's computer, it briefly displays a "Err" message instead of the value of the gauge. This is commonly seen when the ignition is switched from RUN to OFF. Turning the ignition off actually turns the power off to the vehicle's computer. In this situation, UltraGauge does not receive a response and the "Err" message is briefly displayed. This is normal and has no negative effects.
This message can actually be helpful if it is seen during normal operation. It indicates that your vehicle's computer could not respond. This could point to an intermittent issue with your vehicle, that has gone unnoticed. In general it can be ignored. However, if it should become more pronounced such that "Err" is often seen, a more significant problem with your vehicle may exist. This is especially true with vehicles supporting the CAN protocol. Check with your dealership to see if there are any applicable service bulletins.