If you have a diesel engine, you may have noticed a DEF warning light on your dash. This light reminds you to add Diesel Exhaust Fluid to your vehicle, as it helps reduce emissions. While the light may be annoying, it’s straightforward to reset. In this blog post, we’ll show you how to do a DEF warning light reset in just a few simple steps.
What is the DEF Warning Light?
The DEF warning light indicates that your vehicle’s diesel exhaust fluid (DEF) level is low. When the light illuminates, you must add more DEF to the tank to continue operating your vehicle.
If you ignore the warning and continue driving without adding DEF, eventually, the vehicle will go into “limp mode” and will be significantly restricted in terms of speed and power. In some cases, the vehicle may not be able to move at all.
Fortunately, resetting the DEF warning light is a relatively simple process. All you need to do is add more DEF to the tank and drive the vehicle for a short distance until the light turns off.
What Does It Mean When the DEF Warning Light Comes On?
When the DEF warning light comes on in your car, it means that the diesel exhaust fluid level is low and needs to be refilled. Diesel exhaust fluid is used to reduce emissions from diesel engines, and it needs to be refilled regularly in order to keep the engine running correctly. If you see the DEF warning light, stop at a gas station or service center as soon as possible to refill the fluid.
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How to Reset the DEF Warning Light?
If your DEF warning light has come on, it means that the system needs to be reset. Here’s how to do it:
- Turn the key to the ON position without starting the engine.
- Press and hold the accelerator pedal for five seconds.
- Start the engine and release the accelerator pedal.
- Drive for at least 15 minutes to give the system time to reset itself.
What to Do If the DEF Warning Light Won’t Reset?
If you’re having trouble resetting the DEF warning light, you can try a few things. First, make sure that the vehicle is turned off and the key is out of the ignition. Next, locate the fuse box and find the fuse for the DEF system. Once you’ve found the fuse, remove it and inspect it for any signs of damage. If the fuse looks in good condition, reinstall it and see if that does the trick.
If the problem persists, there could be an issue with the DEF pump or electronic control module. Taking your vehicle to a qualified mechanic or dealership for further diagnosis and repair is best.
If your DEF Warning Light is on, don’t panic. You can usually reset the light by topping off your DEF tank or driving for a period without using the cruise control. If you’re still having trouble, you can take your car to a dealer or an authorized service center, and they can help you. Thanks for reading, and feel free to leave any questions or comments below!
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FAQs About DEF Warning Light Reset
How do you reset a DEF fluid light?
In the event that your car’s DEF warning light starts flashing, don’t panic. Simply pour a gallon of DEF into your car, let it idle for a few seconds, and then drive around to make sure the sign has gone away.
Can I drive with the DEF light on?
Combining DEF with diesel gas reduces environmental harm. As for whether it is safe to drive with the DEF light on, yes, it is.
Why does my DEF light stay on?
When the DEF Lamp is illuminated, it indicates that the DEF level is low and needs to be refilled. If this light flashes, the DEF level has fallen below a critical threshold and requires immediate attention. Refilling the DEF tank should rectify these issues.
What does the DEF warning light mean on Mercedes?
When the engine is running, the diesel exhaust fluid warning light will illuminate as an indication that either a malfunction has occurred with the exhaust gas after-treatment system or that DEF levels have dropped too low, become contaminated, or thinned. The warning light will remain constantly lit when a fault has been detected within the system.