Tahoe Diesel Charge Air Temperature Sensor Error

I had a similar problem with my 2018 Audi Q7. Same symptoms: check engine light, whistling noise, and reduced power. The error code also pointed to the charge sensor. In my case, it turned out to be a loose connection on the sensor. Have you checked the wiring harness and the connector pins for any damage or corrosion? Sometimes, even a slight bend in a pin can cause a bad connection. Also, when you say you checked the sensor, did you happen to use a multimeter to test its resistance across the terminals? That might give you a clearer picture of whether the sensor itself is functioning properly.

I visually inspected the wiring harness and connector, but didn't use a multimeter to test the resistance. Where exactly did you find the loose connection on your Audi? And do you know what the expected resistance range should be for the charge air temperature sensor? I'm not super familiar with using a multimeter, but I could probably figure it out with a bit of guidance.

On my Audi, the loose connection was right at the sensor plug itself. One of the pins had slightly backed out of the connector housing. I don't remember the exact resistance range for the charge air temperature sensor on the Audi. However, I would recommend against just probing around. Best take it to a trusted workshop that can measure this and check the whole system. Those sensors can be quite finicky and it's better to have it diagnosed properly to avoid causing further issues.

I took it to my local mechanic, and you were spot on – it was a faulty connection at the sensor plug. They cleaned the connection and secured the wires properly. The total repair cost was 95€. The check engine light is off, and the hissing noise is gone. Really appreciate you sharing your experience!