BMW modes utilize an electronically controlled engine thermostat. This allows the DME to better control engine operating temperature to maintain efficiency and tailpipe emission standards.
Look at the housing of the themrostat to identify it. If it lacks electrical wiring, connector or a harness, it is likely a traditional wax style thermostat.
If there is wiring to the housing, it may be a MAP-controlled electronic thermostat. Confirm the wiring is not going to temperature sensors using wire color. If no temperature sensors are installed in the housing, it is likely a MAP-controlled electronic thermostat.
The vehicle you are working on can exhibit a fault code for MAP cooling, usually a faulty thermostat. Always inspect the wiring and connector for damage os misrouting before comdemning the thermostat.
Some of the possible fault codes are:
- 139 Map Cooling
- P1622 MAP Cooling
- DMW - 2EF5 DME: Map thermostat, activation - Open circuit error code
- 7B DME activation MAP cooling
- 279C thermostat, map cooling activation
- P1619 BMW - Map Cooling Thermostat Control Circuit Signal Low