P040D Code: Exhaust Gas Recirculation Temperature Sensor “A” Circuit High

Exhaust gas recirculation (EGR) temperature sensors monitor the temperature of the gasses entering and exiting the EGR cooler. They send their readings on exhaust gas temperature to the engine control module (ECM) or powertrain control module (PCM).

If the PCM receives an impossibly high voltage signal from the EGR temperature sensor “A,” its diagnostics will log a P040D code.

What Does the P040D Code Mean?

The diagnostic trouble code (DTC) P040D indicates “Exhaust Gas Recirculation Temperature Sensor ‘A’ Circuit High.”

The EGR redirects gasses going through the exhaust system back to the engine. The recirculated exhaust mixes with fresh air and undergoes combustion once more.

The EGR directs the gasses into the EGR cooler, which lowers the exhaust gas temperature.

The EGR temperature sensor is a resistor-type device that measures the temperature of the exhaust gasses before and after passing through the EGR cooler. Then, it converts the reading into a voltage signal and sends it to the PCM. Using the reading, the controller can change the amount of exhaust going to the engine by adjusting the EGR valve.

The PCM compares the EGR temperature sensor ”A” readings with a range of values programmed into its memory. If the voltage is too high, it will set the generic code P040D.

Note: The definition of code P040D can differ according to the vehicle manufacturer. Check the appropriate repair manual or repair database for the exact code definition.

What are the Common Causes of the P040D Code?

• Damaged or faulty EGR temperature sensor
• Circuit issues, such as a damaged wire or poor connection
• An issue with the PCM, such as software in need of an update

What are the Common Symptoms of the P040D Code?

• Illuminated check engine light
• Vehicle lacks power or has other engine performance problems

How to Diagnose the P040D Code

The P040D code is a generic code that applies to all makes and models with an on-board diagnostics system. While various vehicles can log the code, the specifics can change between cases, so there is no single solution for it.

If you’re not confident about conducting diagnostic tests on your vehicle, it’s a good idea to bring it to a professional mechanic who you trust. Otherwise, you can go ahead and diagnose the issue yourself.

How to Fix the P040D Code

To fix a P040D code, you will need the appropriate tools and relevant knowledge to replace the faulty EGR temperature sensor “A.” It’s highly recommended to leave the job to experienced mechanics.

For DIYers with advanced technical knowledge and hands-on experience who prefer to test and replace their vehicle’s EGR temperature sensors on their own, it’s a good idea to consult a repair manual or refer to an online repair database. These resources have vehicle-specific repair information.

Delivering Your New EGR Temperature Sensor to Your Home

We recommend leaving your vehicle in the garage until you can replace its bad EGR temperature sensor. Driving with a faulty part might damage the engine, creating more problems. Fortunately, you don’t have to drive to a shop to get a replacement EGR temperature sensor because CarParts.com delivers to your doorstep.

When you purchase a product from CarParts.com, our nearest warehouse processes your order and ships your new part to your home. If you live anywhere in the continental US and order by noon ET, your replacement EGR temperature sensor will reach you within several business days. We also make finding an EGR sensor that fits your car easy–simply enter your vehicle’s details into our website’s integrated vehicle selector. Got any questions about our products? Our capable customer service team is available 24/7 to help you.

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