P1250low severityPowertrain
Early Fuel Evaporation Heater Circuit
on 2004 GMC Yukon 5.3L V8 Vortec · RWD
What this code means
The PCM detected a malfunction in the Early Fuel Evaporation (EFE) heater circuit. The EFE system heats the intake to aid fuel vaporization during cold starts. The PCM checks EFE heater resistance with the heater off (should be above 2.5V) and on (should be below 0.3V).
Symptoms
- Check Engine Light
- Rough idle when cold
- Poor cold-start performance
- Increased cold-start emissions
- Poor fuel economy in cold weather
Common causes
- Failed EFE heater element
- EFE heater control circuit open
- EFE heater ignition power circuit open
- Corroded EFE heater connections
- PCM failure (rare)
Diagnostic steps
- Test EFE heater element for continuity
- Check control circuit voltage
- Test ignition power supply to heater
- Inspect wiring and connectors for corrosion
- Monitor EFE circuit with scan tool
Repair notes
Test EFE heater element resistance. Replace heater if open. Check power supply and control circuit wiring.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1