Engine Coolant Temperature Sensor 1 Voltage Out Of Range
The engine coolant temperature sensor is sending a voltage reading that's outside normal parameters.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The engine coolant temperature sensor measures how hot the coolant is. If it sends a signal that says the coolant is too hot or too cold (like below -40°F or above 230°F), the computer gets confused and triggers this fault code.
What the computer is actually seeing
The computer expects the coolant temperature sensor to produce a voltage signal between 0.5 volts (cold) and 4.5 volts (hot), corresponding to a temperature range of about -40°F to 260°F.
What a healthy reading looks like
Coolant temperature should typically range from 180°F to 220°F during normal operation, with corresponding sensor voltage around 0.5V to 4.5V.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Check coolant level; ensure it's within normal limits. Decision: If low, top up coolant and retest. If okay, proceed to next step.
- 2Inspect the coolant temperature sensor wiring for damage, frays, or shorts. Decision: Repair any damaged wiring. If wiring is good, proceed to the next step.
- 3Measure the voltage at the coolant temperature sensor connector with the key on, engine off (KOEO). Decision: If voltage is significantly out of expected values (0.5V to 4.5V), replace the sensor. If within range, proceed to the next step.
- 4Check the resistance of the coolant temperature sensor at various temperatures to ensure it changes as expected (should be 2000 ohms at 32°F, 175 ohms at 212°F). Decision: If resistance values are out of range, replace the sensor. If values are good, consider the ECM.
Common causes
- Faulty coolant temperature sensor
- Wiring issues (shorts or open circuits)
- Corroded connector pins
- Coolant leaks affecting sensor performance
- ECM software issue
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
With a moderate severity code, it’s best to avoid driving until it’s fixed to prevent overheating or further engine damage.
Will this code come back after clearing it?
If the underlying issue isn't fixed—like a faulty sensor or wiring issue—the code will likely return.
Why does this code appear together with others like SPN 110?
Multiple codes often point to related issues; for example, if coolant temperature is incorrect, it can affect multiple readings.
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