Circuit Description

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. However, it is still accessible from the selected car via links, so may be relevant.

Engine Coolant Temperature (ECT) sensor monitors temperature of the coolant. This input is used by PCM for engine control and as an enabling criteria for some diagnostics.

The airflow coming into the engine is accumulated and used to determine if engine has been driven within conditions that would allow engine coolant to heat up normally to thermostat regulating temperature. If coolant temperature does not increase normally or does not reach regulating temperature of thermostat, diagnostics that use engine coolant temperature as enabling criteria may not run when expected. This DTC will only run once per ignition cycle within the enabling conditions. If engine coolant fails to reach a preset target temperature before a calculated airflow is accumulated, DTC P0128 will set.