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.
DTC 43, Fuel Temp Circuit High (Low Temp Indicated): Notes
Fuel temperature sensor is a thermistor that controls signal voltage to PCM. When fuel is cold, sensor resistance is high, and PCM will sense a high signal voltage. As fuel warms, sensor resistance becomes less and voltage drops. Fuel temperature sensor is integrated with optical sensor.
DTC 43 will set when fuel temperature is less than 6°F (-14°C) and engine has been running for at least 2 minutes. PCM will default to poor idle quality during hot conditions.
- This step determines if DTC 43 is result of a hard failure or an intermittent condition.
- This step simulates a DTC 42. If PCM recognizes low signal voltage (high temperature), PCM and wiring are okay.
- This step determines if an open is present in fuel temperature signal circuit. 5 volts should exist at sensor connector. This will determine if a wiring problem exists or if PCM is faulty.
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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.