Circuit/System Description: P0037
WARNING: This page is about a different car, the 2010 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.
The ECM monitors the voltage on the HO2S 2 heater low control circuit for heater fault diagnosis. If the ECM detects that the HO2S 2 heater low control circuit voltage is below a specified range, DTC P0037 sets.