Temperature Sensor 1 Out of Range
The temperature value from sensor 1 is outside the expected range.
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)
Your truck's computer thinks the temperature sensor is reporting a weird number, either too low or too high, which doesn't match what it should see.
What the computer is actually seeing
The engine control module (ECM) is receiving temperature data from Sensor 1. If it's below -40°C (-40°F) or above 125°C (257°F), it throws this code, indicating a malfunction in the sensor or its readout.
What a healthy reading looks like
Sensor 1 should read between -40°C (-40°F) to 125°C (257°F) under normal operating conditions.
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. Inspect the wiring and connectors for Sensor 1. Look for damage, corrosion, or loose connections. Fix any issues found. Decision: Are the connections and wiring good? (YES - go to step 3, NO - repair and retest)
- 22. Check the resistance of the temperature sensor with a multimeter. At ambient temperature (around 20°C or 68°F), the resistance should be approximately 2,000 to 4,000 ohms. Decision: Is the resistance in range? (YES - go to step 3, NO - replace the temperature sensor)
- 33. Clear the code and run the engine to observe the temperature reading. Use a scan tool to monitor the live data. Decision: Is the temperature reading now within the expected range? (YES - problem solved, NO - consider replacing the ECM)
Common causes
- Wiring issues such as shorts or opens to the sensor
- Faulty temperature sensor
- Corrosion or bad connectors
- Poor ground connection on the sensor circuit
Typical repair cost
$$ - $$$
Related codes
Frequently asked questions
Can I keep driving with this code?
It's not recommended, as it could affect engine performance and emissions.
Will this code come back after I clear it?
If the underlying issue isn't fixed, it likely will return.
Why does this code pair with SPN 660?
Both codes relate to temperature sensor issues, typically stemming from similar causes.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
Start guided diagnostic →