2018 peterbilt 567 ambient air sensor?

Code : Spn 171 Fmi 2
Ambient Air Temperature Not Plausible: Ambient Air Temperature Data Erratic, Intermittent Or Incorrect;
Ambient Temperature Sensor Data Erratic
I'm not a tech. I think it maybe a 5V sensor power supply issue.
That voltage should have been checked first.
Recommended:
Check the voltage, the sensor, the connecters and harness.
1 Ambient Air Temperature sensor only on this truck.
Good luck.
Let us know if it helped. Or not.

 

Do you have any other fault code that may cause the de-rate?
Can the tech try to reset first all codes active and inactive and see what it does?

 

I

The sensor should feed a reading into the ECM.
Is it possible that a connector or a wire is interrupted going from the sensor to the ECM?
Normally is checked with a multi tester set on Ohms
with batteries disconnected to cut power to the ECM.
While firmly shacking the harnesses to look for bad wiring or just connectors.
All connectors should be visually inspected then cleaned up with a solution.

 

The ambient temp sensor - check near the intake charge pipe - it communicates with the ecm - controls/ feedback the fuel pressure sensor - assuming this is an isx

 

MX-13 uses mirror as ambient air temp sensor. The humidity sensor does also read turbo compressor inlet pressure, temp, and relative humidity. Need to hook up to a good scanner or Davie.