P2181 Diagnostic for 2005 Audi A4 1.8T: Sensor or Thermostat Issue?
Vehicle details: 2005 Audi A4 1.8T with OBD-II fault code P2181. Symptoms include the engine light illuminating, but the vehicle runs smoothly without overheating. The coolant temperature gauge typically reads 0, though it intermittently activates and then deactivates. Coolant levels must be topped up regularly, yet no visible leaks are present. Is this a faulty coolant temperature sensor or a failing thermostat? Seeking expert insight on root cause diagnosis and repair options.
Perform a pressure test on the cooling system to identify any hidden coolant leaks. If leaks are found, address them promptly to ensure accurate diagnosis of the P218或1 fault.