What is the function of the engine coolant temperature (ECT) sensor, and how can a faulty sensor affect starting and fuel trims?

• A. It measures oil temperature
• B. It controls the radiator fan speed only
• C. It monitors exhaust gas temperature
• D. It tells the ECU engine temperature to adjust fuel and ignition; a faulty sensor can cause improper fuel trims, rough cold start, or stalling

Answer: (D)