Engine Coolant Temperature Sensor 2 Circuit Low Voltage
Indicates a low voltage from the engine coolant temperature sensor 2.
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What it means (plain English)
The engine coolant temperature sensor 2 measures the coolant temperature and sends a signal back to the engine computer. If it reports low voltage, it usually means that there's a problem with the sensor or its wiring, like a short or a break.
What the computer is actually seeing
The engine computer expects a voltage signal from the sensor between 0.5V and 4.5V, corresponding to temperatures from about -40°F to 248°F (-40°C to 120°C). It sees a voltage below 0.5V instead.
What a healthy reading looks like
A properly functioning ECM receives a signal between 0.5V to 4.5V from the sensor; at 200°F (93°C), the expected output is around 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 to the coolant temperature sensor 2 for damage or corrosion. Decision: If damaged, repair or replace. If not, proceed to step 2.
- 22. Check the resistance of the coolant temperature sensor at ambient temperature. Expected value at 68°F (20°C) is around 2.7kΩ. Decision: If out of range, replace the sensor. If in range, proceed to step 3.
- 33. With the ignition on, use a multimeter to measure the voltage at the sensor connector. It should be between 0.5V and 4.5V. Decision: If the voltage is below 0.5V, check for shorts to ground. If voltage is as expected, check the ECM.
Common causes
- Faulty coolant temperature sensor 2
- Damaged wiring or connectors
- Short to ground in the sensor circuit
- Poor electrical connection between sensor and ECM
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's generally safe to drive, but the engine may run poorly or overheat. Fix it soon.
Will this code come back after clearing?
If the underlying issue isn't fixed, yes, this code is likely to return.
Why does this code appear with others like SPN 6734?
They often appear together because they involve related sensors or systems monitoring the engine temperature.
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