Mustang NOx Sensor Failure

Okay, NOx sensor issues on the 'Stang... Common enough. The exhaust leak could definitely be related, messing with the sensor readings. First thing, check the wiring harness and plug connection to the NOx sensor itself. Give 'em a wiggle, see if the light flickers or the error code changes. Also, inspect the cable for any obvious damage like cuts or frayed wires. Are you getting any specific error codes besides just 'NOx sensor failure'?

Good call on the wiring harness. I'll give that a look-see tomorrow when it's light out. As for the specific codes, yeah, there's one stored: P2201 NOx Sensor Circuit Range/Performance Bank 1. Does that narrow things down at all?

P2201 confirms the NOx sensor circuit issue. Given the exhaust leak symptom, it's very likely the sensor is getting contaminated, or the wiring is compromised due to the leak's heat. While you can try cleaning the sensor connector and checking for voltage, with that code and mileage, plus the leak, it might be time to bite the bullet. Considering the potential for further damage to the catalytic converter if the NOx sensor isn't reading correctly, a workshop visit for a proper diagnosis and replacement is probably your best bet.

Appreciate the insight, man. Seems like I'm past the point of a simple fix. Took it to the shop and you nailed it - faulty connection on the NOx sensor. They charged me 95€ for the repair, not too bad all things considered. Thanks again for pointing me in the right direction!