Most cars today have a washer fluid warning symbol to warn you if your reservoir is already low. The dashboard symbol helps you avoid having to experience using your wipers with no washer fluid coming out from the nozzles.
However, like any other sensor, if it fails, there is a tendency where the low washer fluid warning stays on. In this guide, we’ll provide detailed, step-by-step instructions how to reset wiper washer fluid sensor.
Understanding How the Washer Fluid Sensor Works
The wiper fluid sensor is a device used to detect the washer fluid level in the reservoir of a vehicle’s windshield wipers. It communicates with the ECU to determine the level of your washer fluid.
There are different types of wiper fluid sensors, but typically they work by using a magnetic float inside a cylinder casing, with a reed switch built into the sensor’s base.
When the washer fluid level drops below the minimum, the float sinks to the bottom of the cylinder. Then the magnet will activate the reed switch. Here’s a very illustrative video from OMEGA Engineering to help you visualize how washer fluid sensors work:
Symptoms of a Bad Washer Fluid Sensor
Like most of the sensors in your vehicle, the wiper fluid sensor may fail due to an electrical or mechanical problem or even because the sensor itself has been damaged.
Here is a list of the common symptoms that you have failing wiper fluid sensor:
- Windshield fluid warning light stays on – If the warning light is always on, even after refilling, it could be inaccurate reading from a faulty wiper fluid sensor. The same can be said if the low washer fluid light isn’t turning on when it’s supposed to be on.
- Strange noises from the washer pump – This could mean the fluid level is low, causing the pump to overheat and the sensor to fail at detecting the level. If you hear strange noise coming from the washer pump without a low washer fluid symbol on your dashboard you may have a faulty sensor.
- Wiper blades won’t turn on/off – The sensor not sending the proper signal to the wiper motor could result in the blades not functioning.
- Dropping washer fluid level – When the level drops below the minimum, it could be due to a faulty sensor that fails to detect the change. This can cause the float to sink and the magnet to activate the reed switch.
Why Low Washer Fluid Warning Light Stays On
As discussed above, the washer fluid warning light staying on even though the reservoir is full can be due to a faulty washer fluid level switch or sensor.
The washer fluid level switch could be stuck or broken, or the washer fluid level sensor could malfunction.
Since the sensor works by passing a small charge from one of its probes to the other through the fluid, if the fluid level drops below the sensor probes, the charge cannot pass through the air, causing the warning light to go on.
Before ordering a new sensor, it is recommended to inspect it to see if there are any wrong issues with it, such as cracked wires.
How to Reset a Faulty Wiper Sensor
Several methods have been suggested for resetting the low washer fluid light, but it’s important to note that these methods may vary depending on your vehicle’s specific make and model.
Here are the top 5 methods to reset the low wiper fluid warning symbol:
- Refill – Fill up the washer fluid reservoir with your favorite brand or even a DIY wiper fluid. If the light is still on, it might be a faulty sensor that needs to be repaired. You should refill the wiper fluid every month so that you can avoid running dry.
- Clean the washer fluid sensor – If the sensor is covered in gunk, you can remove it from the tank and flush it with hot water and a mild solution of white vinegar. You may also dump hot (not boiling) water into the reservoir to clear any gunk around the sensor. Use an compressed air nozzle to agitate the water, then drain it all.
- Replace the washer fluid sensor – If the methods above didn’t work, you may have to replace the washer fluid sensor entirely.
How to Replace a Washer Fluid Sensor
To replace the washer fluid sensor, you’ll need a few tools such as a floor jack, jack stand, lug wrench, multi-bit driver set, and ratchet/sockets. Here’s the basic process:
- Lift and support the vehicle using the floor jack and jack stand.
- Apply the parking/emergency brake.
- Place the jack at the appropriate lifting point for whichever side you are working on.
- Locate the washer sensor, which is typically located at the bottom of the washer fluid tank.
- If the sensor is stuck inside the cylinder, tapping lightly on the washer fluid tank may help free it.
- If the washer fluid sensor fails, it will have to be replaced.
- In some vehicles, the sensor is held by a rubber grommet, which makes replacement fairly easy.
Here is a helpful tutorial from speedkar99 which can provide more detailed guidance:
A faulty washer fluid sensor can cause the low washer fluid light to turn on, even when the reservoir is full. You can fix the issue yourself by checking for leaks and repairing them or by replacing the sensor. It is important to keep the washer fluid level full and contact a local certified mechanic if warning signs are recognized.