TechShop’s The Code Reader Podcast takes common DTCs, breaks down when and why they occur and looks at symptoms and causes to help listeners make an accurate diagnosis.
ASE certified technician and Managing Editor of TechShop Magazine, Eric Garbe discusses diagnostic trouble code P0128.
DTC P0128 is stored when the control unit recognizes that the engine does not reach operating temperature within a predetermined amount of time.
When an engine is cold, emissions are high. Until completely warmed up to operating temperature, the engine runs rich for driveability and the catalytic converter(s) will not operate at their maximum efficiency, therefore it is critical for an engine to reach operating temperature as quickly as possible in order to reduce emissions. The fuel management system is strategically programmed to decrease warm up time, and the control unit compares coolant temperature and run time to make sure it falls within expected parameters.