my aem wideband sensor went bad after about 11k miles of use but a lot of leaded race fuel use in that as well. The aem doesnt need to be calibrated. You just have to replace the sensor at least once a year depending on driving and fuel used.
Plain and simple. They did the testing as far as widebands go and the innovate was the leading and most accurate followed by the aem which was the cheapest one out there and best for the price.
The sensor is about 65 shipped, why not replace it every year. BTW if its .7 off and your comparing to a shops tailpipe reading then thats stupid. The wideband will be more accurate than the tailpipe sniffer anytime. If they were using their own wideband sensor as well as yours then either yours or theirs was too old. A lot of shops dont replace theirs until they crap out completely and most cars that run on their dynos are probably running race fuel. leaded at that.
My aem worked perfectly for the 1 1/2 years 11k miles i used it and then just all of a sudden it started reading slow and it was a quick downhill from reading slow to hardly even moving at all no matter the load, rpm, or what. Knew it was time to be replaced. Simple as that.
Nothing wrong with the AEM wideband. Great gauge for the money. Its been tested to be very accurate. Not the most accurate but definitely not .7 off I think it stayed within .1-.2 at the most during the testing. The innovate was dead on to no more than .1 off.