Engine Temperature Sensor 2 - Voltage Below Normal
This code indicates that the second engine temperature sensor is reporting a voltage lower than expected.
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 computer is checking the temperature from the second sensor, and it's seeing a lower voltage signal than it should—usually less than about 0.3 volts when it should be higher, indicating a potential issue with the sensor or wiring.
What the computer is actually seeing
The engine control unit (ECU) expects the second temperature sensor to output a voltage corresponding to a certain temperature. For example, at 75°C (167°F), the output voltage should typically be around 0.8 to 1.5 volts. If it sees less than 0.3 volts for prolonged periods, it will flag SPN 2563.
What a healthy reading looks like
At normal operating temperatures, expect 0.5V to 1.5V depending on the temperature. Below 0.3V triggers the fault.
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 second engine temperature sensor for corrosion or damage.
- 22. Use a multimeter to check the voltage output of the second temperature sensor. Disconnect the sensor and measure across the signal and ground pins. Should see around 0.5V to 1.5V at normal operating temperatures.
- 33. If voltage is below 0.3V: Inspect the wiring harness or connectors for shorts or breaks. Repair as necessary. Recheck the sensor output after repairs.
- 44. If voltage is normal after repairs, replace the second engine temperature sensor and retest.
- 55. If sensor replacement does not resolve the issue, inspect the ECU and consider updating the software.
Common causes
- Faulty engine temperature sensor 2
- Wiring issues (shorts or opens)
- Corrosion or poor connection at the sensor or ECU
- Damaged or out-of-spec thermostat
- ECU software issue
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive with this code?
It's best to fix this code soon; driving may not cause immediate danger, but it can lead to incorrect engine performance or overheating.
Will the code come back after clearing it?
If the underlying issue isn't fixed, yes, the code is likely to return.
Why does this code show up alongside SPN 2562?
SPN 2562 indicates a voltage above normal for the first engine temperature sensor, which can occur in conjunction with issues affecting temperature readings.
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 →