Audi A6 engine fails to restart when warm, likely due to faulty coolant sensor on Audi A6

Some Audi A6 owners report experiencing difficulties with their engine failing to restart when warm, which may be linked to a faulty coolant sensor. These issues can manifest as intermittent cranking failures, where the engine does not crank at all and no sounds are heard during the start attempt. Additionally, owners note that high fuel temperatures above 78 degrees and coolant temperatures above 84 degrees can negatively affect the starting process. A weak or dead 12V battery is often identified as a likely cause when the engine either won't crank or cranks slowly, and conducting a battery voltage test can help confirm this. Furthermore, some owners experience clicking sounds when attempting to start, indicating that while there is sufficient charge for the solenoid, the battery may lack enough power for the starter. Addressing these concerns, such as checking the coolant sensor and ensuring the battery is functioning properly, is crucial for resolving the warm restart issue in the Audi A6.