P1250 - FAULT CODE - OBD2

P1250 BUICK, CADILLAC, CHEVROLET, GMC: EARLY FUEL EVAPORATION HEATER CIRCUIT

The Early Fuel Evaporator is a device belonging to the fuel system in internal combustion engines equipped with carburetors. In some vehicles, it is known as an electronic fuel evaporator or EFE heater, which is located between the carburetor throttle body and the intake manifold. This heater has a resistance grid that is heated by the air/fuel mixture. It helps with fuel vaporization under cold weather conditions. It also reduces exhaust emissions as it runs for two minutes, allowing for tighter throttle calibrations.

The P1250 OBDII diagnostic code is specific. In the case of GMC, Chevrolet, and other brand vehicles, it is set when the engine is running and the BARO input is above 75 kPa, the IAT (Intake Air Temperature) input between 14 and 122°F and the fuel level above 25%. The Powertrain Control Module (PCM) detects that the Early Fuel Evaporation (EFE) resistor circuit voltage is below 2.5v with the EFE heater off, or the EFE heater voltage is greater than 0.3v with the heater on for more than 5 seconds.

• Check Engine light ON.

The P1250 OBD2 fault code is set for these reasons:

• The Early Fuel Evaporation (EFE) resistor wiring or connectors may be damaged.
• The electrical connections of the EFE resistor circuit may be faulty.
• The Early Fuel Evaporation resistor may be defective.

To troubleshoot DTC P1250 OBDII, try this:

• To start the diagnosis, please refer to the Technical Service Bulletins.
• Check the EFE resistor for damage to its wiring or connectors. If common deficiencies are found, make the necessary repairs.
• Verify that the early fuel evaporator resistor circuit voltages are within the parameters set by the manufacturer. If these do not match those specified by the manufacturer, make the appropriate corrections, including the replacement of the evaporator if necessary.