Diagnostic Aids
WARNING: This page does not describe the selected car, but rather 13 other vehicles, including the 2003 Hummer H2, 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 GMC Sierra, and 2003 GMC Cab & Chassis Sierra. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0125 is designed to detect a skewed ECT sensor or a faulty thermostat.
Excessive coolant flow through the by-pass hose to the throttle body may cause this DTC to set.