Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Coolant Temperature Override (CTO) Switch
Coolant temperature override (CTO) switch is located in coolant passage at cylinder head or coolant passage at intake manifold.
Inner port of switch is connected to EGR port on intake manifold and outer port is connected to EGR valve, or EGR-TVS. Switch opens at a preset temperature. Below these temperatures, no EGR is possible.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.