- The common symptoms of an obstructed transmission filter include abnormal shifting, noises from the transmission pump, and contaminated transmission fluid.
- The PCM will also illuminate the check engine light and record a diagnostic trouble code (DTC) if it detects a transmission issue caused by low fluid pressure.
- The symptoms could vary depending on the vehicle’s year, make, and model.
Automatic transmissions have a transmission filter (or strainer) that traps contaminants and debris before they circulate throughout the transmission. On many vehicles, the filter is a maintenance item that requires routine replacement.
If the filter is not serviced in accordance with the vehicle manufacturer’s maintenance schedule, it may eventually become obstructed, resulting in one or more noticeable symptoms.
How Does a Transmission Filter Work?
All automatic transmissions have a filter made of paper and/or synthetic materials (or a strainer made from woven metal). The filter is located in the transmission fluid pan and positioned at the transmission pump’s inlet.
When the vehicle’s engine is running, the pump, which is driven off the engine by the torque converter, starts pulling fluid from the pan through the filter. From there, the pump pressurizes the fluid and distributes it to the various passages in the transmission’s valve body. The pressurized fluid acts on the control devices (clutches and bands) that cause the transmission to shift gears.
The transmission filter is important because it traps contaminants so that they do not enter the pump and get distributed throughout the transmission. Unfortunately, the role of the transmission filter makes it susceptible to obstruction from dirt and debris.
When the filter becomes obstructed, the pump will be starved of fluid, resulting in a low fluid pressure condition inside the transmission.
Clogged Transmission Filter Symptoms
Many other problems can mimic an obstructed transmission filter. What’s more, filters often become clogged due to internal transmission problems that result in excessive debris. So, you (or your mechanic) should diagnose the vehicle thoroughly before assuming the filter is to blame for any of the symptoms listed below.
With that in mind, let’s take a look at the most common symptoms of a clogged transmission filter.
One of the most common signs of a clogged transmission filter is abnormal shifting. Automatic transmissions often begin to “slip” when one or more of the control devices fail to hold due to low fluid pressure. This slippage results in an increase in engine RPMs without an increase in vehicle speed. You may also notice other shift quality issues if the transmission filter is clogged.
Noise from the Transmission Pump
An obstructed transmission filter can starve the pump of fluid, causing the pump to make a whining noise that coincides with engine speed.
Burnt or Contaminated Transmission Fluid
If the filter is obstructed, the transmission will experience overheating due to lack of lubrication. As a result, the fluid will often be dark in color and smell burnt. Once the transmission pan is removed, you may also find signs of excessive friction material and/or metal debris in the bottom of the pan.
Illuminated Warning Lights
On modern vehicles, the transmission control module (TCM) monitors transmission operation. If the module detects a problem with the transmission due to low fluid pressure, the device will turn on the check engine light and store a diagnostic trouble code (DTC) in its memory. Some vehicles may also turn on a separate transmission warning light when there’s a problem.
Transmission Filter FAQ
A transmission filter cannot be unclogged—it must be replaced. The good news is, replacing a transmission filter or transmission strainer is generally a fairly inexpensive and straightforward repair, as long as there hasn’t been any subsequent damage to the transmission.
As is noted above, a clogged transmission filter must be replaced. A professional repair shop will typically replace the filter as part of a transmission service. Usually, the service will cost somewhere between $150 and $300. Of course, the exact cost will vary depending on a variety of factors, such as the year, make, and model of your vehicle.
Also, it’s important to point out that the transmission may have suffered internal damage as a result of the clogged filter. In such a scenario, the transmission will either need to be rebuilt or replaced—and that can cost thousands of dollars.
Get a Top-Notch Transmission Filter for Your Ride
A clogged transmission filter can cause issues like abnormal shifting and transmission fluid contamination, which can lead to a plethora of problems that are hard to fix. If yours is clogged or obstructed, don’t think twice about replacing it. Find and order a new transmission filter for your ride in minutes here at CarParts.com.
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Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.