How To Test a Nissan 350Z ECT Sensor

How To Test a Nissan 350Z ECT Sensor


The engine computer in your Nissan determines the engine temperature using the coolant sensor. This unit is also known as the 350Z ECT sensor, and it’s a two pin sensor mounted near one of your fuel pressure regulators. The sensor in your 3.5 liter V6 engine is basically a thermistor that uses resistance to operate.

Because the ECT sensor is meant to detect the engine coolant temperature, it plays a huge role for your engine computer. Using this sensor your Nissan engine computer will know when your engine is at the right operating temperature. Based on this signal your cooling fans and fuel maps can work correctly.

When your 350Z ECT sensor goes bad, your Nissan will run poorly. The Nissan 350Z problems that arise from a bad sensor aren’t always obvious, but your check engine light is. When you need to fix your 350Z check engine light, you’ll first need a OBDII scan tool to retrieve the code.

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Today I’ll be showing you how to test your coolant sensor in a 2007 Nissan 350Z. This vehicle currently has a check engine light for the P0117 OBDII trouble code. The specific language behind this code is Engine coolant temperature sensor circuit low input.

This basically means that there’s an excessively low voltage from the sensor that’s being sent to your Nissan engine computer. Because this engine sensor uses an internal resistance to determine the coolant temperature, we’ll be using a digital multimeter to test it.

How Does the 350Z ECT sensor work?

This is a thermistor device that’s sensitive to the change in temperature. When your coolant temperature rises in your engine, the internal resistance of the thermistor decreases. This change is represented in a voltage change and that’s how your Nissan ECU understands how hot the engine is.

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Symptoms of a failed 350Z ECT sensor

  • Bad gas mileage
  • Engine cooling fans won’t turn on
  • Engine overheating
  • 350Z engine computer stuck in cold fuel map
  • Check Engine Light ON

Testing your 350Z ECT sensor

You can do this one of multiple ways but we’ll start with the easiest method first. Open your 350Z hood and locate the ECT sensor, which is nearby your front fuel damper. Disconnect the two pin ECT harness and you’ll be using your multimeter to see if there’s power.

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Once you’ve got the engine coolant sensor disconnected, you can test for voltage. Turn your 350Z ignition to the “ON” position. Put the black lead on the negative terminal of your batter, and then gently test PIN 1.

Reference our 350Z ECT Sensor wiring diagram before doing this.

If you have power at this wire, the next step is to measure the internal resistance of your coolant temperature sensor. This can also be done one of two ways, but if your OBDII trouble code is for a lack of ECT signal there’s only one real way you need to test it.

With your engine coolant sensor disconnected, turn your multimeter to read resistance Ω and probe the two pins at the sensor itself.

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With your engine at room temperature, the resistance at this sensor should be between 2.1 – 2.9 kΩ.

If you don’t have this base resistance, it means your 350Z ECT sensor has died. Remove your old unit and install a replacement Nissan coolant sensor.

If the OBDII check engine code in your 350Z is showing a low or high voltage like our 2007 model is, you can take one step further in our How To Testing guide.

This 2007 350Z has the P0117 OBDII trouble code, which again is for low input from your ECT. With the coolant temp sensor removed, you’ll be testing the resistance of the sensor again. But this time you’ll be using a cup of hot water to test or measure the operation of your sensor.

To give you a good idea of what this resistance should be, use varying degrees of hot water. At 122 degrees Fahrenheit, the measurement at these two pins should be 0.68 – 1.00 kΩ. Try pouring in cold water to your hot water cup and watch the resistance rise slowly. This Nissan ECT has an operating range all the way up to 194 degrees Fahrenheit, which it should read a resistance of 0.236 – 0.260 kΩ.

If your 350Z ECT Sensor doesn’t respond in this manner, it’s time to ditch it and install a new coolant temperature sensor. Have any questions about our 350Z ECT Sensor How To Guide? Leave us a comment below and let us know!