Normal temperature variations can overstate your emissions. When the
test box temperature was raised from 70F to 90F, the standard electrochemical
sensor erroneously reported a concentration of 47 PPM of NO gas when no gas was
present. This change is the result of the interaction between temperature
and a sensor's history of exposure. The SEM sensor is temperature controlled
per EPA's CTM-022 Sec 7.2.1
(Electronic manipulation of a sensor's output would
understate emissions and is "unacceptable" per CTM-022 Sec 2.3.1)
