Circuit Description

PCM will richen air/fuel ratio when a high coolant temperature is monitored. The Hot Fuel Enrichment (HFE) condition can cause exhaust emissions to exceed Federal emissions standards. This DTC is required in order to prevent HFE from being active during a skewed ECT sensor condition or during an actual cooling system problem causing a hot engine condition.

PCM will calculate ECT value based on IAT, engine speed, vehicle speed and engine load. If ECT value is higher than calculated coolant temperature, DTC P1483 will set and HFE is disabled.