Bought this 30-4110 in March of last year,sat in the box for 8 months while I finished the car.Just started the Rambler(LS Turbo) at Thanksgiving and consistently displayed 15.5 to 16.2.( 14.7 unplugged) After following the instructions on testing a sensor with Brakekleen, it was determined the sensor was not responding. A call to AEM and they are shipping me a new gauge and sensor. I am very impressed with how they handled this. just wanted everyone to know how to test them. It is basically testing open air and the gauge should read full lean, saturating a cloth with the flammable brake Cleaner, wrapping the end of the sensor and the gauge should sweep to full RICH.

https://www.youtube.com/watch?v=rmnxKLjM25g