How to Reset Service Def System See Dealer

How to Reset Service DEF System See Dealer: A Comprehensive Guide

The Diesel Exhaust Fluid (DEF) system is an essential component in modern diesel engines. It helps to reduce harmful emissions by injecting a urea-based solution into the exhaust stream, converting harmful nitrogen oxides into harmless water vapor and nitrogen gas. However, there may be occasions when your vehicle’s DEF system requires attention, leading to the dreaded “Service DEF System See Dealer” message. In this article, we will guide you through the process of resetting the service DEF system and provide answers to 12 common questions related to this issue.

Resetting the Service DEF System:

1. Determine the issue: Before resetting the DEF system, it’s important to identify the root cause of the problem. This can be done by using an OBD-II scanner to read the error codes associated with the DEF system.

2. Fix the problem: Once the issue has been identified, it is crucial to rectify it before resetting the DEF system. Some common problems include DEF level sensor failure, contaminated DEF fluid, or a malfunctioning DEF pump.

3. Disconnect the battery: To reset the DEF system, start by disconnecting the vehicle’s battery. This will clear any stored error codes and reset the system.

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4. Wait for 15 minutes: After disconnecting the battery, wait for at least 15 minutes to ensure that any residual electrical charge has dissipated.

5. Reconnect the battery: Reconnect the battery and start the vehicle. The “Service DEF System See Dealer” message should no longer be displayed. However, if the issue persists, it is recommended to seek professional assistance.

Common Questions and Answers:

1. Why did the “Service DEF System See Dealer” message appear?

The message appears when there is a problem with the DEF system, such as a faulty sensor, contaminated fluid, or a malfunctioning pump.

2. Can I continue driving with the message displayed?

It is generally safe to drive with the message displayed, but it is crucial to address the issue as soon as possible to prevent further damage to the engine.

3. How often should I refill the DEF tank?

The frequency of refilling the DEF tank depends on various factors such as vehicle usage and driving conditions. However, it is recommended to refill the tank when the DEF level drops to around 30%.

4. Can I use any brand of DEF fluid?

It is advisable to use DEF fluid that meets the ISO 22241 standard. Using a reputable brand ensures the quality and proper functioning of the DEF system.

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5. How do I know if the DEF fluid is contaminated?

Contaminated DEF fluid may appear discolored, contain floating particles, or emit a foul odor. If you suspect contamination, it is best to drain and refill the DEF tank.

6. Can I reset the DEF system without disconnecting the battery?

Disconnecting the battery is the most effective way to reset the DEF system. However, some vehicles may allow for a system reset through the infotainment system or by using specific buttons on the dashboard. Refer to your vehicle’s manual for instructions.

7. What if the “Service DEF System See Dealer” message reappears after resetting?

If the message reappears after resetting the DEF system, it indicates that the underlying issue has not been resolved. It is recommended to consult a professional technician for a thorough diagnosis.

8. Does resetting the DEF system affect my vehicle’s warranty?

Resetting the DEF system does not void your vehicle’s warranty. However, any modifications or repairs made to the system should be performed by authorized service centers.

9. Can I manually check the DEF fluid level?

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Most vehicles have a DEF level gauge that displays the fluid level on the dashboard. Consult your vehicle’s manual to locate and interpret the gauge.

10. Can I use tap water to top up the DEF fluid?

Using tap water to top up the DEF fluid is not recommended, as it may contain impurities that can damage the system. Always use fresh DEF fluid.

11. How long does it take to reset the DEF system?

The process of resetting the DEF system usually takes a few minutes. However, it is important to wait for at least 15 minutes after disconnecting the battery to ensure a complete reset.

12. Is it possible to prevent DEF system issues?

Regular maintenance, using high-quality DEF fluid, and adhering to the manufacturer’s recommendations can significantly reduce the likelihood of DEF system issues.


Resetting the Service DEF System See Dealer is a relatively straightforward process that involves disconnecting and reconnecting the vehicle’s battery. However, it is vital to address the underlying issue causing the message to appear. By following the troubleshooting steps and consulting a professional if necessary, you can ensure the proper functioning of your vehicle’s DEF system and contribute to cleaner air.