How to replace an engine coolant temperature sensor?

The engine coolant temperature (ECT) sensor measures coolant temperature in the cooling system, allowing the PCM to control spark timing and fuel mixture. The ECT sensor is a high authority sensor when the engine is cold because the ignition timing is tailored to the engine coolant temperature. It also provides inputs for idle air control (IAC) position, oxygen sensor closed loop status, tank purge on/off time and idle speed.

Signs of a faulty engine coolant temperature sensor

There is no doubt that ECT sensors also fail over time. Its failure can lead to a host of problems, including overheating and poor engine performance. Therefore, it is important to know how to spot a faulty ETC sensor. Here are some signs that there may be a problem with the ECT sensor.

Hard engine start

The PCM relies on the ECT sensor to control the spark timing and the amount of fuel injected into the engine, so if the sensor fails, you may have difficulty starting the engine.

Black smoke emission

A faulty ECT sensor can cause the PCM to produce a richer fuel mixture than normal. When excess fuel burns in the exhaust pipe, thick black smoke may be produced.

Poor mileage

If the ECT sensor sends the wrong signal to the PCM, the computer can create the wrong air-fuel mixture, causing the engine to consume too much fuel.

Rough idling

Incorrect fuel mixing due to a faulty ECT sensor can cause the vehicle to have a rough idle.

How to replace an engine coolant temperature sensor?

Different types of ECT sensors are available on many sites, such as, MyMRO provides the ETC sensor 4954905 for Cummins engine dodge ram 2500. Meanwhile, the ECT sensor replacement is a simple process for anyone who is familiar with the components of an engine.

Step 1: Locate the sensor location

The ECT sensor is usually located at the front of the engine, near the radiator or engine thermostat housing. You may need a lamp or flashlight to find it. Removing the hood can also helpful.

Step 2: Remove the Connector Cables from the Terminals

The ECT sensor is connected to the ECU by a connector, you need to unhook and remove the connector carefully as the plastic connectors and wires are often fragile and will require a complete replacement if broken.

Step 3: Unscrew and remove the old sensor

The coolant sensor is like a spark plug, so you need to unscrew it to remove it. Using the deep socket and ratchet, carefully loosen the sensor counterclockwise without applying too much pressure. Once the sensor is loose, unscrew it by hand, remove it from the socket.

Step 4: Install the new sensor

Use a rag or cloth to clean up areas of dust and debris that could affect the performance of your new ECT sensor. Put the new sensor into the threads and turn clockwise by hand to make sure the sensor is well seated in the socket. Then, use a torque wrench to tighten the sensor to the amount specified in the manufacturer's instructions.

Step 5: Recover the Connector Cable

Once the new sensor is in place, the only thing left to do is reconnect the cables. Make sure the connector is clean and free of debris, then carefully insert it into the new sensor, carefully tightening any clips to ensure a good connection to the terminals. You’d better start the engine and as it warms up, monitor the temperature gauge on the dash to make sure it's maintaining the correct temperature.