Volvo All Engines (2010 Emissions) Fault Code: SPN 177 FMI 16 PID: Transmission Oil Temperature – Moderately Severe Level

The J1587 and J1939 serial data lines are used as the standard communication link for on-board vehicle instrumentation, off-board service diagnostics and fleet management.
The transmission oil temperature sensor sends a signal to the instrument cluster module which relays a signal to the engine control module (ECM) via the data link. The signal is used to demand fan activation. If the transmission oil temperature gets too high, a yellow check lamp or red stop lamp will illuminate. The engine will also derate.

Probable cause
1) Low oil level, Transmission
2) Oil temperature sensor
3) Oil cooler
4) Transmission overloaded