Engine Coolant Overtemperature Protection Mode Active
2002-2009 GMC Envoy 4.2L I6
Description
The PCM has activated engine protection mode due to excessive coolant temperature. The PCM may reduce power output, disable cylinders, or limit RPM to prevent engine damage from overheating. This is a serious code that requires immediate attention.
Symptoms
- Reduced Engine Power message
- Engine overheating
- Temperature gauge in red zone
- Loss of power
- Engine may shut down
- A/C system disabled
Common Causes
- Low coolant level
- Failed water pump
- Stuck closed thermostat
- Blocked radiator
- Faulty coolant temperature sensor
- Head gasket failure
- Cooling fan failure
- Collapsed radiator hose
Diagnostic Steps
- Check coolant level immediately
- Inspect for coolant leaks
- Test thermostat operation
- Check water pump for flow
- Test cooling fans
- Inspect radiator for blockage
- Pressure test cooling system
- Check head gasket (combustion gas test)
Repair Notes
Do not continue driving. Check coolant level and look for leaks immediately. Continued overheating will cause severe engine damage including head gasket failure and warped heads.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
P1258 on Other Vehicles
Common Questions
What does code P1258 mean on a 2002-2009 GMC Envoy?
P1258 stands for "Engine Coolant Overtemperature Protection Mode Active". The PCM has activated engine protection mode due to excessive coolant temperature. The PCM may reduce power output, disable cylinders, or limit RPM to prevent engine damage from overheating. This is a serious code that requires immediate attention.
What are the symptoms of P1258 on a GMC Envoy?
Common symptoms of P1258 include: Reduced Engine Power message, Engine overheating, Temperature gauge in red zone, Loss of power, Engine may shut down, A/C system disabled.
What causes P1258 on a 2002-2009 GMC Envoy?
Common causes of P1258 include: Low coolant level, Failed water pump, Stuck closed thermostat, Blocked radiator, Faulty coolant temperature sensor, Head gasket failure, Cooling fan failure, Collapsed radiator hose.