P1656

P1656

Coolant switch-over valve driver, open circuit

Diagnostic conditions
- Supply voltage > 7 V
- Engine running
- Coolant change-over valve not activated (ATF cooler open)
- for 997 coolant temperature > 100 °C (212 °F) or ATF temperature > 90 °C (194 °F)
- for 987 coolant temperature > 90 °C (194 °F) or ATF temperature > 90 °C (194 °F)

Possible fault causes
- Open circuit in the control line
- Coolant switch-over valve faulty
- DME control module faulty