Nissan TITAN XD DEF engine fault due to NOx sensor replacement needed after dash warning on Nissan TITAN XD

Some Nissan TITAN XD owners report experiencing DEF engine faults related to NOx sensor issues, which can trigger the Malfunction Indicator Lamp (MIL) and store specific Diagnostic Trouble Codes (DTCs) such as P22A7, P229E, P221A, and U059F. These DEF system errors may lead to serious problems, including engine shutdown, melted particulate filters, and warning lights on the dashboard. To address these issues, owners are advised to first check the DEF fluid level and quality. In some instances, resolving the DEF system problems may require replacing the NOx sensor or the entire tank, with sensor replacement costs estimated around $1,500. It is recommended that affected owners have their vehicles inspected by a qualified technician to accurately diagnose and address the necessary repairs.