[BMW 520i 2015]

Hi, i have a 2015 520i, the computer check shows thermostat error (car is not heating up nor is the coolant leaking or less) the workshop mechanic said to replace both pump and thermostat together (car done 60000 km or 55k miles)

second mechanic read the code and asked to change only the thermostat and not the pump as there is no error code for WP! I'm confused as WP is quite expensive! any input from experts will be appreciated.

thanks

Rajat