P0634

Symptoms

• The Check Engine light comes on
• Emergency mode or reduction in engine power
• Malfunctions of various systems during long driving
• The code appears after a long period of driving in a traffic jam
• Possible unstable operation of the ECU at high air temperatures

Causes

• Incorrect location of the ECU close to heat sources
• Coolant leak on the ECU housing
• Engine cooling system malfunction
• Clogged engine compartment ventilation system
• Internal defect of the ECU - increased heat generation

How to Fix

1. Make sure the ECU is positioned correctly and is not near the exhaust manifold
2. Check the cooling system for leaks and if the engine is overheating
3. Check for thermal shields near the ECU
4. Check engine compartment ventilation
5. At normal engine temperature - diagnostics of the internal ECU sensor
6. Consider installing an additional heat sink on the ECU housing

Related codes

Error P0634 by Vehicle Brand