Data Validity - Engine Coolant Temperature Sensor 1
Indicates a problem with the engine coolant temperature sensor signal.
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 control unit (ECU) is getting a temperature reading from the coolant temperature sensor that doesn't make sense—it might be too high or too low for normal operation.
What the computer is actually seeing
The ECU looks for a voltage range from the coolant temperature sensor between 0.5V (around -40°C) and 4.5V (around 125°C). If it reads below 0.5V or above 4.5V, it triggers SPN 2555.
What a healthy reading looks like
For normal operation, the coolant temperature sensor should produce a voltage of approximately 0.5V at -40°C and 4.5V at around 125°C. Typical operating temperature should show voltage between 0.7V and 2.5V.
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.
- 11. Inspect the wiring and connectors for the coolant temperature sensor. Check for corrosion, damage, or loose connections. If any are found, repair or replace as necessary. Decision: If wiring is good, proceed to step 2.
- 22. Measure the voltage output from the coolant temperature sensor with the engine at operating temperature. Expected voltage should be between 0.7V and 2.5V. Decision: If voltage is within range, check the ECU; if out of range, replace the coolant temperature sensor.
- 33. If the sensor was replaced, clear the code and test drive the vehicle to see if the fault returns. Decision: If the code comes back, suspect a wiring or ECU issue.
Common causes
- Faulty coolant temperature sensor
- Wiring issues or broken connections
- Grounding problems
- Engine overheating conditions
- Faulty ECU
Typical repair cost
$$ (100-400)
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to address this code soon since it can affect engine performance and fuel economy.
Will this code come back after I clear it?
If the cause isn’t fixed, the code will likely return.
Why does this code sometimes appear with engine overheating?
Overheating can lead to faulty signals from the sensor, causing the ECU to trigger this code.
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