The P065D: Reductant System Malfunction Lamp Control Circuit code refers to an issue with the control circuit for the reductant system malfunction lamp, which alerts the driver when there is an issue with the reductant system (typically found in diesel vehicles to reduce emissions using DEF or AdBlue). This issue may stem from a faulty lamp control circuit, wiring problems, or a defective lamp itself.
P065D – Quick Overview
| Code | Information |
|---|---|
| Meaning | P065D: Reductant System Malfunction Lamp Control Circuit |
| Is it serious? | No, but it prevents the driver from being properly alerted to reductant system issues, potentially leading to higher emissions or system failure. |
| Possible causes | – Faulty reductant system malfunction lamp control circuit – Wiring issue – Faulty reductant system lamp |
| How to diagnose? | – Test reductant system malfunction lamp control circuit – Inspect wiring and connectors – Replace reductant system lamp if necessary |
P065D Meaning
The P065D code signifies a problem with the control circuit for the reductant system malfunction lamp, which indicates issues in the vehicle’s DEF (Diesel Exhaust Fluid) or AdBlue system. If the lamp is not functioning properly, the driver may not be alerted to issues in the reductant system, leading to increased emissions or engine performance problems if left unchecked.
Step-by-step diagnostic guide
| Action | Description | Tools Needed |
|---|---|---|
| Check for Other Codes | Use an OBD-II scanner to check for additional codes related to the reductant system, which may give further insight into potential system malfunctions. | OBD-II Scanner |
| Test the Reductant System Malfunction Lamp Control Circuit | Use a multimeter to test the voltage and continuity in the reductant system lamp control circuit. Ensure the circuit is delivering the correct signal to the lamp. | Multimeter |
| Inspect Wiring and Connectors | Inspect the wiring and connectors leading to the reductant system lamp for signs of damage, corrosion, or loose connections. | Flashlight, Multimeter |
| Test the Reductant System Lamp | Test the lamp itself to ensure it is functional and capable of illuminating when commanded by the control circuit. Replace if faulty. | Diagnostic Tool, Multimeter |
| Replace the Reductant System Lamp if Necessary | If the reductant system lamp is found to be defective or non-functional, replace it to restore the warning system’s functionality. | Replacement Lamp, Tools |
| Clear the Code and Test | After repairs, clear the code using an OBD-II scanner and test the vehicle to ensure the lamp and control circuit are working correctly. | OBD-II Scanner, Vehicle Manual |
Free PDF: How to choose OBD2 scanner
I’ve made you a free PDF to choose the OBD2 scanner in 5 minutes.
✅ Which OBD2 scanner is best?
✅ Which type should you get (DIY, Pro, Hobby)
✅ What is the best scanner for the exact brand/feature (e.g best for BMW)
✅ How to get a Bi-Directional tool for as cheap as $40
✅ Discount coupons for scanners
PDF is 100% free and it is designed to help you pick a scanner in less than a few minutes! Not a boring 50-page guide.
Just tell me where to send it.
Hi, I am Juraj “Yuri” Lukacko. I got frustrated by unhelpful and scammy mechanics, so I decided to learn everything about car diagnostics myself. I test dozens of new car diagnostic tools every month along with learning new strategies to fix and customize cars. About Juraj Lukacko (Yuri)