What is an EGR Valve Temperature Sensor and where is it Located?

The exhaust gas recirculation (EGR) valve temperature sensor helps to control the function of the EGR valve. To reduce engine emissions, modern vehicles have exhaust gas recirculation systems. These systems route gasses from the exhaust to the intake, which reduces the combustion temperatures in the engine. Reduced combustion temperatures minimize nitrous oxide emissions and prevent engine knocking. 

Sometimes though, recirculating exhaust gasses is more of a hindrance than a help. When the engine is idle, combustion temperatures are naturally lower. So, there’s no need to add exhaust gas, and doing so would lead to a less complete combustion. EGR systems have valves that open and close to allow gasses through when needed and keep them out when they’re not needed.

EGR valves have been controlled in different ways throughout their history. In the past they were often controlled by engine vacuum. Today they are usually controlled by the car or truck’s onboard computer, the Engine Control Unit (ECU). The ECU uses input from different sensors to determine when to open and close the EGR valve.

The EGR valve temperature sensor is one such sensor. It is mounted in the EGR passage between the intake manifold and EGR valve and measures the temperature of the exhaust gasses. The passage temperature will increase when the EGR valve is open and exhaust gases are flowing. As the temperature increases, electrical resistance in the sensor decreases. The ECU is able to interpret this voltage into a temperature and determine whether the EGR valve should be closed or opened. 

How do I Know if my EGR Temperature Sensor Needs to be Replaced?

Ironically, it’s the high heat that an EGR temperature sensor is exposed to that can cause it fail. Frequent shifts in temperature can eventually wear the sensor out. A bad EGR temperature sensor will misidentify the temperature of the exhaust gasses, making the ECU ineffective at correctly operating the EGR valve. 

Usually, this causes the valve to be closed more often than it should. That means exhaust gasses are not being routed to the intake. That makes for higher combustion temperatures, which leads to engine knocking or a pinging to be heard. Knocking can cause damage to the engine. Higher combustion temperatures also increase nitrous oxide emissions which might cause you to fail an emissions inspection. If the EGR system is not operating correctly, often the check engine light may light up. Some common EGR related OBD II codes are:

• P0400 - EGR Flow Malfunction
• P0401- Insufficient EGR Flow
• P0402 - EGR Excessive Flow
• P0403 - EGR Circuit Malfunction

Symptoms of a bad EGR temp sensor can be similar to those of a problem with an EGR valve itself. You might want to test the sensor before you replace it. One way to do this is to put the sensor in water and test the resistance of the sensor with a multimeter as you heat the water. As the temperature rises, the resistance of the sensor should decrease. 

Can I Replace an EGR Valve Temperature Sensor Myself?

Fortunately, replacing the EGR temp sensor is a task that a do-it-yourselfer can complete. The sensor is mounted to the EGR tube. You will need to disconnect the wiring harness for the sensor, and remove it from the EGR tube with a wrench. Then you can thread in the new one, tighten it to manufacturer specifications and plug it in. 

Need an EGR Temp Sensor Replacement?

The EGR valve temp sensor has an important role, and while they are generally durable, the high heat they are exposed to all the time can cause them to fail. If you have determined that your sensor is no longer functional and a replacement is needed, then 1A Auto is the place to go! We carry a large selection of aftermarket EGR valve temp sensors for many makes and models, and at great prices.

At 1A Auto, we make shopping for a replacement EGR valve temperature sensor for your car, truck, SUV or van easy - we're here to help you select the right part for your vehicle! Call our customer service toll free at 888-844-3393 if you have any questions about our aftermarket EGR valve temperature sensors, warranty, compatibility or to purchase, or you can buy online.