7 Most Common DeWalt 20v Trimmer Problems: Diagnosis + Fixes

DeWalt 20v trimmers have powerful engines and gear-drive transmissions that quickly power through weed overgrowth. However, several users have reported having a treacherous time with these trimmers. The most common Dewalt 20v trimmer problems are problematic starts, ragged cuts, overheating, stalling, noise, problematic gears, and swath complications.

Do you own a problematic Dewalt trimmer? Keep reading as we dissect the leading Dewalt 20v trimmer issues and their fixes.

Problematic Starts

Most Dewalt 20v trimmers refuse to power on at some point. The leading causes of this problem include incorrect opening mechanisms, dead batteries, bad battery chargers, poor connections, and dirty air vents.

Powering Dewalt 20v trimmers involves pushing their lock-off levers and squeezing the speed trigger. Always ensure the lock-off lever is completely pulled back before pushing the trimmer’s speed trigger for easy starts.

Dewalt trimmers depend on the batteries’ energy to function. Always check the batteries’ charge by trying them on another tool and charge them immediately if they have a low voltage. Avoid running down your Dewalt battery, as it could cause irreversible damage.  

You should also check if the battery has any leaks. Reduced acid levels cause the battery to malfunction. Repair the cracked area or replace the battery with a new one if irreparable.

A faulty battery charge doesn’t supply batteries with adequate power, causing them to get depleted fast. A charging battery keeps flickering. If yours flickers once and then goes off, high chances are that it’s damaged. Replace defective battery chargers to avoid this problem.

Poor connections cause the trimmer’s battery to malfunction due to a constricted power flow. Always ensure the battery is attached correctly to the trimmer for a smooth energy flow.

You should also ensure that the pins connecting the battery to the trimmer are clean. These pins easily collect dirt and debris when trimming. Clean them regularly to prevent this inconvenience.

A dirty air vent restricts the flow of sufficient and clean air into the system, jamming the trimmer. Dust, dirt, and debris build up in the vent when trimming. Clean this trimmer component after every three uses to curb these inconveniences.

For the best results, clean the vent using an air compressor that features a blower nozzle. Clean the vent’s outside using a horsehair brush.

Ragged Cuts

Uneven cuts are common with Dewalt 20v trimmers. These tools are about nine pounds and are handheld. After long working periods, your grip will loosen and get shaky, resulting in an uneven cut. Trim your lawn in bits to avoid these Dewalt 20v trimmer problems. 

Dewalt trimmers use monofilament lines instead of conventional blades featured in other brands. These filaments’ strings rotate fast to get rid of grass in challenging-to-reach areas in your lawn.

Faulty strings result in uneven cuts, as they cause a high disturbance when working. Cheap and low-quality strings are prone to wearing out fast and malfunctioning. Stick to high-quality string brands to prevent this problem.


Dewalt 20v trimmers run at an outstandingly high RPM, meaning the engine is always in high operation and produces lots of heat. The trimmer’s engine is equipped with extra safeguards like a proper exhaust system to maintain the trimmer’s temperatures and allow you to use it comfortably.

Monitor the trimmer’s exhaust system and replace it if damaged to prevent burning yourself when in operation.

Cleaning the vents is also crucial to ensure the exhaust system functions properly. Vents let in clean and adequate air, helping the exhaust system function properly. With time, they clog due to dirt and dust buildup.


Your Dewalt trimmer may sometimes have trouble getting to its full speed. The leading cause of this problem is not pulling the variable speed trigger all the way. The trigger’s level is vital in determining speed. Always depress the trigger’s level before setting off to prevent this problem.

A clogged spool doesn’t rotate smoothly, slowing down the trimmer. Clean the spool after every use to curb dirt buildup.


The Dewalt 20v trimmer blades are metallic and vibrate during work. When loose, they clang against each other and other trimmer components, producing lots of noise. Tighten the blades or let a mechanic take a look and fix them if you can’t do it.

Thanks to their rough surfaces, old blades are also prone to clanging and producing excessive noise. Replace these for quiet operations.

Extreme vibrations also lead to excessive noise. The primary cause of intense vibration is uneven cutting lines. These may result from one end of the string hitting something sharp and breaking. To fix this, extend the shortened line so it’s equal on both sides.

A clogged or broken head pool could also result in uneven lines. Regularly clean the spool and replace it if broken to solve this issue.

Problematic Gears

Dewalt 20v trimmers come with low-quality grease on their gears. The cheap lubricant dries up after a few uses and clumps together, causing the gears to strain when moving. Dried-up grease also causes the gears to wear out fast and malfunction.

Fixing this problem involves cleaning all the old grease off the gears and applying the right amount of high-quality grease.

Avoid applying excess grease on the gears, as it causes more Dewalt 20v trimmer problems. Too much grease forms huge lumps or clogs when dried, preventing gear movement. 

Ensure you reinstall the gearbox properly afterward to prevent other difficulties when running your trimmer.

Swath Complications

Dewalt trimmer swaths can be problematic when positioned wrongly. Swath represents the trimmer’s radius. A short swath prevents cutting deep into the grass, while an extended one could turn off the trimmer abruptly.

Maintaining the swath at three hundred and thirty millimeters or thirteen inches is advisable for enhanced efficiency.

Dewalt 20v Trimmer Maintenance

Regular maintenance is crucial to prevent frequent Dewalt 20v trimmer problems. Below are some important tips to follow.

  • Regularly check the cooling fins and clean them to prevent clogging.
  • Check if there’s any damage to the cooling fins and replace them immediately to curb overheating and engine damage.
  • Regularly check all the electrical connections and clean them in case of any dirt buildup to prevent damage and constricted power flow.
  • Examine all gears and apply adequate grease to prevent them from burning out and wearing out fast.
DeWalt 20v trimmer problems


Use the tips discussed in this article to troubleshoot DeWalt 20v trimmer problems. Keeping a maintenance schedule is key to preventing most of these issues.