You can skip this section if you bought your LC-1 after June of 2006.
First… If there is a voltage differential or any other cause that would pull your 5v output to anything above 5v it could burn out the DAC on the older model LC-1. Wired properly most people never had a problem with them but Innovate proactively made the circuit more robust, replaced faulty units and provided an updated version of the product. Their handling of this issue was truly a class act.
The ‘older model’ LC-1’s were up until about June 2006, in white/beige box. The new models were sold since then and Innovate updated the packaging at about the same time to a blue/black box and later still to a white/red box. The more definitive way is to determine which model you have is to check the serial number. The serial for the LC-1s with the analog output fix are LC11188 forward and all LC-1s that start with CLC. Note that in fall 2007 Innovate started using a white/red box, these are still the new LC-1’s, just using a different box design.
Bottom Line: Wiring it according to the docs is the most important thing. Not just for longevity but for accuracy as well. You don’t want a voltage differential in your readings so you definitely want to ground your LC-1 at the same point as your ECU (assuming you’re feeding the output back into the ECU) or datalogger if that’s what you’re using. Then ground the heater ground to a separate point as per the docs. This will make even the old LC-1’s last forever in our experience.