Engine Temperature Sensor Circuit Low Voltage
Engine temperature sensor is reporting low voltage.
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What it means (plain English)
The engine temperature sensor should send a voltage between 0.5V and 4.5V, usually around 1.0V to 2.5V when the engine is at normal operating temperature, but it's currently sending a much lower voltage, indicating a potential short or failure.
What the computer is actually seeing
The computer detects a voltage below the expected range from the engine temperature sensor. This can affect performance and emissions because the engine control unit (ECU) relies on this data for fuel mixture and timing adjustments.
What a healthy reading looks like
0.5V to 4.5V from the engine temperature sensor under normal operating conditions; ideally around 1.0V to 2.5V when the engine is warmed up.
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 wiring and connectors for the engine temperature sensor; look for frays or corrosion. Decision: are they okay? (yes/no)
- 22. If wiring is good, measure the voltage at the engine temperature sensor with a multimeter with the engine running. Expected voltage should be between 0.5V and 4.5V. Decision: do you see this voltage? (yes/no)
- 33. If voltage is below 0.5V, replace the engine temperature sensor. If voltage is okay, suspect an ECU issue.
Common causes
- Wiring issues (short to ground)
- Faulty engine temperature sensor
- Corroded connector pins
- ECU malfunction
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's drivable, but engine performance may be compromised; fix it soon.
Will this code come back after I clear it?
If the root cause isn't fixed, yes, it will return.
Why does this code sometimes pair with SPN 1001?
SPN 1001 is often related to coolant temperature; a problem with the temperature sensor can trigger both codes.
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