Q: What does the powertrain malfunction/reduced power (RTT) Warning Light mean?

The Powertrain malfunction/reduced power is a warning that is illuminated when the vehicle is experiencing a condition - that if driven can cause damage to the engine, transmission or drivetrain. The warning is to let you know to decrease the load on the vehicle (typically speed) and is close to defaulting into a limp home mode for protection if it has one. Typically with this warning a code is set in one of the component located in the powertrain (engine control, transmission or traction control/ABS). It is possible that if it keeps occurring that it can activate another warning. If the problem resolves itself the warning may go away.

For example, if you have a heavy load, perhaps towing a trailer, and are going up a hill, and the transmission is starting to overheat. To avoid further damage the warning “Powertrain malfunction/reduced power” is illuminated to warn you to take steps like ease off the load to avoid overheating the transmission. If you decide to ignore this warning the vehicle may go into a limp home mode where the computers will cut back on the throttle and operate in a safe mode it knows is safe till the issue has been resolved, and the transmission temperature has cooled down.