Engine Coolant Temperature Sensor 1 - Voltage Above Normal
The engine coolant temperature sensor reading is too high.
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 computer thinks the coolant is way hotter than it should be, possibly leading to overheating.
What the computer is actually seeing
The engine control module (ECM) reads a voltage signal from the coolant temp sensor; normal readings range from 0.5V to 4.5V corresponding to a temperature of -40°C to 125°C. A voltage above 4.5V indicates a problem.
What a healthy reading looks like
Coolant temperatures should be between 80°C to 100°C (176°F to 212°F) during normal operation.
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.
- 11. Check the engine coolant level. If low, top it off and see if the code returns.
- 22. Inspect the wiring and connectors at the coolant temperature sensor for damage or corrosion. Repair or replace as necessary.
- 33. Measure the voltage at the coolant temperature sensor with a multimeter. It should be within 0.5V to 4.5V. If it's above 4.5V, replace the sensor.
- 44. If the sensor is good, check for proper operation of the thermostat. It should allow coolant to flow at the correct temperature. Replace if stuck.
Common causes
- Faulty engine coolant temperature sensor
- Wiring issues or short circuits in the sensor circuit
- Thermostat malfunction causing overheating
- Poor engine cooling system maintenance
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's not safe to drive for long, as overheating can lead to serious engine damage. Fix this soon.
Will this code come back after clearing it?
If the underlying issue is not resolved, yes, the code will likely return.
Why does this code sometimes pair with SPN 111 or SPN 1731?
Those codes relate to the same system - they could indicate sensor issues or further cooling system problems.
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