P0634moderate severityPowertrain
PCM/ECM/TCM Internal Temperature Too High
on 2018 Ram 3500 6.7L I6 Cummins · RWD
What this code means
The control module detected an internal temperature above the safe operating limit. This can cause the module to shut down or run in a protected mode.
Symptoms
- Intermittent engine performance issues
- Module resets or shutdowns
- Check engine light on
Common causes
- Excessive engine bay heat
- Poor module mounting/ventilation
- Internal module fault
- Faulty cooling near module
Diagnostic steps
- Read module internal temperature data
- Inspect module location and heat sources
- Check for cooling airflow obstructions
- Replace module if internally faulty
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
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
P0005
Fuel Shutoff Valve A Control Circuit/Open
P0006
Fuel Shutoff Valve A Control Circuit Low
P0007
Fuel Shutoff Valve A Control Circuit High
P0008
Engine Position System Performance - Bank 1
P0009
Engine Position System Performance - Bank 2
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1