Powertrain
generic / SAE
P0634
Control Module Internal Temperature A Too High
The ECU measures its own internal temperature and reports the value above the safe upper threshold - typical for a heat-soaked engine bay, blocked airflow around the ECU, or a failing internal temperature sensor.
SystemPowertrain
Typegeneric / SAE
GroupP0
Range / number6 / 34
Possible causes
- Heat soak around ECU high
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Inspection / repair
- Difficulty: medium
- DIY: shop recommended
- Estimated cost: 80–1000 €
- Estimated time: 0.5–4 h
- Component: ecm
- MIL / check engine light
Sources
References
sae:J2012