It's not recommended to drive your 2015 Cruze 2.0 diesel with a malfunctioning DEF (Diesel Exhaust Fluid) temperature sensor. The DEF system plays an important role in reducing harmful emissions from your vehicle's exhaust, and if the system isn't functioning properly, it could potentially cause damage to your engine or emission system.
If the DEF temperature sensor is not working correctly, it could lead to incorrect readings and cause the DEF system to malfunction. This could trigger a warning light on your dashboard and eventually cause your vehicle to go into a "limp mode," which reduces power and speed.
To prevent any further issues, it's best to get your vehicle to a shop as soon as possible to have the DEF temperature sensor replaced. In the meantime, you should avoid driving your vehicle too far or too hard until the issue is resolved.