Where Is The Fuel Temperature Sensor On A Duramax? [+Fix] (2023)

If you are not a car enthusiast, you may not know the purpose of the fuel temperature sensor. Most people don’t know the importance of that sensor and don’t know where it is. We are here today to help you with that.

So, where is the fuel temperature sensor located on a Duramax? Depending on the engine, it can be found on the rail on the passenger side. It is sometimes on a return fuel line or the rail under the upper intake manifold shield. It is connected to two wires, and that can help you identify it.

Where Is The Fuel Temperature Sensor On A Duramax? [+Fix] (1)

Knowing about this sensor is important because it regulates how much fuel will go to the injectors. It communicates with the ECU. It adjusts the fuel and air ratio based on the temperature of the fuel.

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Understanding the Duramax Engine

Duramax engines brought a revolution to the diesel engine market. These engines are dependable, reliable, and strong. They are made from cast gray iron. The cylinders are made from aluminum, and the connecting rods are forged steel. All elements are constructed to withstand very high temperatures and engine wear.

Older Duramax engines didn’t have a lift pump, which caused problems after adding more horsepower. These engines used only the Bosch CP3 or CP4 pump for pumping fuel. From 2011. that changed when the lift pump was installed in the factory.

All these characteristics made all Duramax engines friendly to upgrades. With the help of EFI Live, and after upgrading several components, owners could easily double the performance of the engine.

See Also: How Much Horsepower Does EFI Live Add

Components of the Duramax engine

The main components of the Duramax engine don’t differ from other diesel engines:

  • The fuel system. It comprises a fuel tank, water separator, feed pump, filter, injection pump, injectors, and cylinders.
  • Lubrication system. It reduces the wear of the moving parts of the engine. It also removes the heat from the pistons and other parts.
  • The intake system. It comprises the air cleaner, turbocharger, intake manifold, inlet port, inlet valve, and cylinder bore.
  • The exhaust system. It is made of a cylinder bore, exhaust valve, port, manifold, turbocharger, and muffler.
  • The cooling system. It optimizes the temperature for the work of the engine. That way, the lubrication properties of the fluids are protected.
  • The electrical system. Its components are the starter motor, alternator, and battery.

Importance of the Fuel Temperature Sensor

The fuel temp sensor is in communication with the ECU, and they regulate the air-to-fuel ratio.

The Role of the Fuel Temperature Sensor in the Duramax Engine

The fuel temp sensor is added to the engine to control the amount of fuel intake. That way, the engine can maintain the best performance. It is always in communication with the ECU. They maintain the fine-tuning of fuel consumption.

How the Fuel Temperature Sensor Works

The sensor has a thermistor that reacts to different fuel temperatures. If the fuel is colder, less of it is needed. It burns slower, and the resistance of the sensor increases. If the fuel is hotter, the ECU sends info that more fuel is needed. Then the sensor reduces the resistance, allowing fuel to flow faster.

Ideally, the temperature of the fuel should be lower than 104°F. Colder fuel becomes denser and burns slower. High fuel temperature is not good for the overall health of the engine.

Locating the Fuel Temperature Sensor on a Duramax

The location of the fuel temperature sensor depends on the model of the engine:

  • On the LB7, the sensor is located on the fuel rail under the upper intake manifold shield
  • On the LLY/LBZ engine, it is located on the fuel rail on the passenger’s side
  • On the LML engine, it can be found near the lower corner of the high-pressure pump
  • On the L5P, the sensor is found on the back of the CP4 pump.

Step-By-Step Instructions on Finding the Fuel Temperature Sensor

Factory-installed temp sensors are usually in the green or sometimes gray color. They are connected with two wires. These wires are in brown and gray colors or some model’s brown and white colors.

Troubleshooting the Fuel Temperature Sensor

Fuel temperature sensors can go bad if the car is exposed to very high temperatures for a long time. Also, overflowing the fuel tank can damage the sensor. Corrosive fuel vapors can also be a cause for the malfunction of the sensor.

Common Issues With the Fuel Temperature Sensor

There are a couple of symptoms that are connected to the faulty temperature sensor. If you notice one or more of these, visit the mechanic as soon as possible.

Poor fuel economy

The sensor is responsible for the amount of fuel sent into the combustion chamber. If you notice that the car is burning fuel faster, that is an almost sure symptom of a faulty sensor.

Jumps in the temperature readings

If you notice that the temperature of the engine is higher or lower than it should be, check the sensor. Sometimes the engine will feel colder and will not warm up as it should

Black smoke coming out of the tailpipe

If the air-to-fuel ratio is wrong, the engine will burn excessive amounts of fuel. That will result in black smoke coming out of the exhaust.

Engine overheating

Problems with the sensor are usually connected to lower engine temperatures. Sometimes the dashboard will be a signal for overheating when the engine is cold. But, the overheating can become constant. That is a sure signal to check the sensor.

Check the engine light

Check the engine light. There are many different reasons for the check engine light to go on. Sometimes the reason is a faulty fuel temp sensor.

How to Diagnose and Fix Issues with the Fuel Temperature Sensor

The best thing to do is to monitor how the engine is running. If you notice any of these strange symptoms, visit the mechanic. Diagnosing the faulty fuel sensor is best done with the OBD II scanner. Also, a mechanic who knows what he is doing can help. Codes that are connected with the failure of the sensor are between P0180 and P0189.

Check Out How To Test and Replace the Fuel Temperature Sensor:

Where Is The Fuel Temperature Sensor On A Duramax? [+Fix] (2)

Maintenance and Replacement of the Fuel Temperature Sensor

The fuel temp sensor is not a frequent problem on Duramax engines. Either way paying attention to its state is essential for the work of the truck.

How Often the Fuel Temperature Sensor Should Be Replaced

Fuel temperature sensor life depends on the climate and outside temperature. A hotter climate will shorten the life of the sensor. Also, try to avoid overflowing the fuel tank. In some cases, the fuel sensor can last as much as 400k kilometers. But in case you notice any problems, replace the sensor as soon as possible.

Step-By-Step Instructions on Replacing the Fuel Temperature Sensor

  1. Depending on the model, locate the sensor
  2. Disconnect the sensor from the electrical connector
  3. Remove any parts that are in the way of accessing the sensor
  4. Remove the safety clip from the fuel line
  5. Use a ¾-inch deep socket to unscrew the sensor
  6. Insert the new sensor into place and screw it in
  7. Connect the sensor to the electrical connector
  8. Return the safety clip to the fuel line
  9. Return all the removed parts to the place.


What Occurs When a Gasoline Temperature Sensor Malfunctions?

When this happens, the air-fuel ratio cannot be good. The sensor is sending more or less fuel into the combustion chamber. If it is not working, the system will get the wrong amounts of fuel. That will impact the overall performance and fuel consumption.

What does the Duramax error code P0181 mean?

The comprehensive component monitor monitors the fuel temp sensor. The error occurs if the voltage falls below or exceeds a limit during the testing.

Final Considerations

The fuel temperature sensor is often an overlooked component. But, it is essential for the proper work of your engine. Without the working sensor, the air and fuel ratio will be wrong, causing several problems. Your engine may not warm up, it may overheat, performance will drop, and it will consume more fuel.

If you notice any symptoms, we highly recommend visiting a mechanic. The OBD II scanner can diagnose different problems with this sensor. From there, the problem can be identified and resolved. Keep your engine healthy for the best overall performance of your truck.

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