Handheld testing device of nitrogen oxide sensor

A testing device for testing a NOx sensor in an environment having a temperature below the dew point, wherein the NOx sensor is disconnected from a system having a controller configured to output one or more verified dew point signals to the NOx sensor indicative of at least one of measured temperature and humidity conditions within the system, the testing device comprising:

• a connector configured to be coupled to the NOx sensor;
• an output indicator;
• and
• circuitry in communication with the connector and the output indicator, wherein the circuitry is configured to:
• send a first signal to the NOx sensor via the connector indicating that a temperature of the environment is at or above the dew point in order to activate the NOx sensor,
• receive a second signal from the NOx sensor via the connector indicating the operation of the NOx sensor in the environment,
• determine a status of the NOx sensor based on the received second signal, and
• indicate, via the output indicator, the status of the NOx sensor.