Transmission Over Temperature Condition
2002-2009 GMC Envoy 4.2L I6 🇨🇦
Description
The TCM detected that the transmission fluid temperature has exceeded the maximum safe operating temperature. Excessive heat is the primary killer of automatic transmissions.
Symptoms
- Check Engine Light
- Transmission may enter limp mode
- Harsh or delayed shifts
- Hot transmission fluid smell
- Possible loss of forward gears
Common Causes
- Low transmission fluid level
- Clogged transmission cooler
- Failed transmission cooler lines
- Towing beyond capacity
- Worn torque converter clutch causing excess heat
- Transmission slipping internally
Diagnostic Steps
- Check transmission fluid level and color
- Inspect transmission cooler and lines for restriction
- Test transmission temperature with scan tool
- Check for transmission slipping
- Inspect torque converter clutch operation
Repair Notes
Check fluid level immediately. Inspect cooler and lines. Do not drive with overheated transmission. If fluid is burnt (dark brown/black with burnt smell), internal damage likely.
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
P1812 on Other Vehicles
Common Questions
What does code P1812 mean on a 2002-2009 GMC Envoy?
P1812 stands for "Transmission Over Temperature Condition". The TCM detected that the transmission fluid temperature has exceeded the maximum safe operating temperature. Excessive heat is the primary killer of automatic transmissions.
What are the symptoms of P1812 on a GMC Envoy?
Common symptoms of P1812 include: Check Engine Light, Transmission may enter limp mode, Harsh or delayed shifts, Hot transmission fluid smell, Possible loss of forward gears.
What causes P1812 on a 2002-2009 GMC Envoy?
Common causes of P1812 include: Low transmission fluid level, Clogged transmission cooler, Failed transmission cooler lines, Towing beyond capacity, Worn torque converter clutch causing excess heat, Transmission slipping internally.