Engine Cooling Temperature Sensor Circuit Low
The engine cooling temperature sensor is reporting a low voltage issue.
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What it means (plain English)
The engine cooling temperature sensor measures the temperature of the engine coolant. When it sends a low voltage reading (below 0.1 volts), the computer thinks the engine is too cold which can cause poor performance and higher emissions.
What the computer is actually seeing
The engine control module (ECM) expects the cooling temperature sensor to produce a voltage signal between 0.5V (cold) to 4.5V (hot). If it sees a voltage below 0.1V for more than 2 seconds, it triggers the trouble code SPN 1564.
What a healthy reading looks like
Normal operating range for the sensor output is 0.5V to 4.5V depending on coolant temperature.
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.
- 1Check the wiring and connectors of the engine cooling temperature sensor for damage or corrosion, repair as necessary. Decision: Is the wiring intact? If yes, move to step 2; if no, repair wiring.
- 2Measure the voltage at the sensor connector while the engine is off and then while running. You should see values between 0.5V and 4.5V. Decision: Is the voltage in range? If yes, go to step 3; if no, replace the sensor or repair the circuit.
- 3Check the engine control module (ECM) for proper operation. Consult manufacturer service manual to run ECM diagnostics. Decision: Is the ECM functioning? If yes, further diagnose the engine temp sensor circuit; if no, replace the ECM.
Common causes
- Faulty engine cooling temperature sensor
- Wiring issues in the sensor circuit
- Bad ECM configuration or failure
- Short circuit to ground in the sensor circuit
Typical repair cost
$$
Related codes
Frequently asked questions
Can I still drive with this code?
Yes, but you may experience poor engine performance and higher emissions.
Will this code come back after clearing it?
If the underlying issue isn’t fixed, yes, it will return.
Why is this related to other codes?
Issues with the cooling temperature sensor can indicate broader problems in engine management.
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