2007 International 4300 Pid171 FMI3 Ambient Air Sensor code

The temp sensor I replaced had a Cummins ISB and a fault code for the temp sensor. Replacing the sensor in the mirror fixed the problem. The engine must get the ambient air temp through the J1939 data link from the instrument cluster.

 

Ok, this is why it is so important for people to tell us exactly what they have, what engine model they have, VIN and so on. I think in this case he has the year or model number wrong. I want to see the VIN before I waste another second on this.
Look at the year and model he is describing. I think he has a DT or VT engine, because I have never seen an ISM in a 4000 series, only 7000 series. DT's(07 MaxxDT) don't have or use an Ambient temp sensor, only the IAT sensor.
In 2007, with an ISM, the ambient temp sensor is hardwired to the ECM. Location not exactly known, but likely near the rad area. The engine and cluster had their own separate sensors until about 2013 and became single on SCR engines. The ambient temp sensor is still hardwired to the engine and sent to the cluster via 1939 on those newer trucks and, yes, it is in the mirror on most of those.

I have attached some info that might be helpful.