By Graham FisherUpdated November 2026
When a DeWalt self drive lawn mower won’t start, the fix is often a single worn or missing part rather than a dead engine. This guide compares five replacement parts and accessories that owners commonly look for when a DeWalt self drive lawn mower won’t start, including a start key, a recoil starter and a safety lever key. We focus on compatibility with listed DeWalt model numbers, build materials, and the feedback patterns owners tend to report. Because nothing here is based on our own bench testing, always confirm the part number against your mower’s label before ordering.
Our top picks at a glance
- 1
TOP CHOICEBest overallLawn Mower Start Key Compatible Models DCMWSP700Y2, DCMWSP650Y2, DCMWSP256U2View on Amazon - 2
TOP CHOICEBest for recoil starter failuresDEWALT 12A-01T9739 Recoil StarterView on Amazon - 3
TOP CHOICEBest for battery-powered modelsGreenworks 40V 16in Push Lawn MowerView on Amazon - 4
Best for a gas self-propelled replacementBILT HARD 21" Self Propelled Gas Lawn MowerView on Amazon - 5
Best budget pickEssential Lawn Mower Start Lever Locking Device 4-PackView on Amazon
Our Top Picks
Quick Comparison
| Product | Best for | Key feature |
|---|---|---|
| Lawn Mower Start Key Compatible Models DCMWSP700Y2 and related DeWalt models | Mowers where the start key is lost or broken | Listed compatibility with several DeWalt model numbers |
| DEWALT 12A-01T9739 Recoil Starter | Pull-start failures and worn starter cords | Heat-resistant, deformation-resistant housing |
| Greenworks 40V 16in Push Lawn Mower | Owners considering a battery replacement mower | Push-button start with no pull cord |
| BILT HARD 21″ Self Propelled Gas Lawn Mower | Owners replacing a failed self drive unit | 201cc 4-cycle engine with 3-in-1 discharge |
| Essential Lawn Mower Start Lever Locking Device 4-Pack | Budget-minded owners who need spare keys | Four-pack for multiple mowers or storage |
Lawn Mower Start Key Compatible Models DCMWSP700Y2, DCMWSP650Y2, DCMWSP256U2
Lawn Mower Start Key Compatible Models DCMWSP700Y2, DCMWSP650Y2, DCMWSP256U2 DCSNP2142B, DCSNP2142Y2 NA262050 Lawn Mower Key fit for DeWalt Lawn Mower
Best for: Owners whose mower will not start because the safety key is missing, worn or not fully seated.
This is a replacement start key listed for several DeWalt model numbers, including DCMWSP700Y2, DCMWSP650Y2 and DCMWSP256U2. It suits anyone whose original key has been lost or whose key no longer engages the start switch.
Key specs
- Designed as a replacement start key
- Listed compatibility with multiple DeWalt model numbers
Pros
- Inexpensive way to restore starting when the key is the problem
- Listing names several compatible models, which helps with matching
- No tools needed for most installations
Cons
- Fit depends on matching the exact model number, so verify before buying
- Does not repair an engine or electrical fault if the key is not the cause
Bottom line: Pick this first if your mower clicks or refuses to crank and you suspect the key. Confirm your model number matches the list.
DEWALT 12A-01T9739 Recoil Starter
fit for DEWALT Lawn Mower 12A-01T9739 Deformation Resistant Housing, Heat Resistant Material, Stable Starting Performance 84010941 Recoil Starter fit for Briggs and Stratton for DEWALT 12A-O1T9739
Best for: Pull-start mowers where the rope will not catch, the cord breaks, or the pawls fail to engage.
This recoil starter assembly is listed for DeWalt part number 12A-01T9739 and is described as fitting Briggs and Stratton-style starting systems. It targets owners whose engine turns over only briefly or not at all when pulled.
Key specs
- Listed for DeWalt part 12A-01T9739
- Housing described as deformation resistant and heat resistant
Pros
- Addresses a common cause of pull-start failure
- Replacement is usually a bolt-on job for a home mechanic
- Heat-resistant housing suits repeated hard pulls
Cons
- Only relevant to recoil-start mowers, not key or battery models
- Installation requires removing the old unit and checking the drive pulley
Bottom line: The right choice if the rope pulls freely but the engine does not catch. Check the part number against your old starter first.
Greenworks 40V 16in Push Lawn Mower
GreenworksQuiet walk-behind mower with push-button start; gas-free operation eliminates fumes and pull starts 40V 16in Push Lawn Mower, 4.0 Ah Battery and Charger
Best for: Owners who want to move away from gas starting problems entirely.
This is a quiet, gas-free walk-behind mower with push-button start, so there is no pull cord or choke to troubleshoot. It is an alternative rather than a repair part, aimed at people who are tired of a DeWalt self drive lawn mower that won’t start.
Key specs
- 40V battery platform, 16-inch cutting deck
- Includes 4.0 Ah battery and charger, per the listing
- Push-button start
Pros
- No fuel, oil or spark plug maintenance
- Push-button start removes the pull-cord failure point
- Low noise and no exhaust for small yards
Cons
- Runtime is limited by battery capacity, which suits small to medium lawns
- Not self-propelled, so it does not replace a drive-assist mower for larger, hilly yards
Bottom line: A good switch for small lawns if you want reliable push-button starting without gas. Expect a different mower style than a self drive unit.
BILT HARD 21″ Self Propelled Gas Lawn Mower
BILT HARD 21" Self Propelled Gas Lawn Mower – 201cc 4-Cycle OHV, 3-in-1 Bagging/Mulching/Side Discharge, 8 Adjustable Cutting Heights & Smooth Easy Start
Best for: Owners replacing a failed self drive mower who want a complete gas unit.
This is a self-propelled gas mower with a 21-inch deck, a 201cc four-cycle overhead-valve engine and a 3-in-1 bagging, mulching and side discharge system. It is a full replacement rather than a repair part.
Key specs
- 21-inch cutting deck, self-propelled
- 201cc 4-cycle OHV engine, per the listing
- Eight adjustable cutting heights, per the listing
Pros
- Complete unit, so no diagnosis of the original engine is needed
- Three discharge modes cover bagging, mulching and side discharge
- Eight height settings suit varied lawns
Cons
- Requires assembly and a full break-in routine
- Replacing the whole mower costs more effort than fixing a single part
Bottom line: The best fit when repair costs or age make replacing the whole machine the smarter option. Compare its features with your current deck size first.
Essential Lawn Mower Start Lever Locking Device 4-Pack
Fits Model DCMWSP244U2 DCMWSP255Y2 DCMWP233U2, Essential Lawn Mower Start Lever Locking Device 4-Pack N835578 Lawn Mower Safety Key Replacement for De-Walt Lawn Mower
Best for: Budget-minded owners who need spare keys or a backup for storage.
This four-pack of start lever locking devices is listed for several DeWalt models, including DCMWSP244U2, DCMWSP255Y2 and DCMWP233U2. It is useful when a key is lost or when you want spares on hand.
Key specs
- Pack of four
- Listed compatibility with several DeWalt model numbers, including N835578
Pros
- Four units cover a backup and extra storage
- Low-cost option for a common failure point
- Easy to swap without tools in most cases
Cons
- Fit must be confirmed against your exact model
- Will not help if the fault is in the engine, battery or starter
Bottom line: A practical choice for spares and for owners who suspect the locking lever is the culprit. Confirm model compatibility before you buy.
Buying Guide
Identify the Starting System First
Before buying any part, determine how your DeWalt starts: a safety key, a pull cord, or a push-button battery system. Owners often report ordering a starter when the real problem was a missing key. Check the model number on the data plate, usually on the deck or near the engine.
Good picks for this: Lawn Mower Start Key for DeWalt Models, DEWALT 12A-01T9739 Recoil Starter
Match the Model Number
Compatibility lists are model-specific. A part listed for one DeWalt number may not fit another, even within the same series. Compare your number character by character with the listing before you add anything to your cart.
Good picks for this: Essential Lawn Mower Start Lever Locking Device 4-Pack, Lawn Mower Start Key for DeWalt Models
Check Materials and Heat Resistance
Starter housings and levers see repeated heat and stress. Parts described as heat resistant or deformation resistant are generally a better bet for frequent use than thin plastic alternatives. Look for these terms in the listing.
Good picks for this: DEWALT 12A-01T9739 Recoil Starter
Decide Between Repair and Replacement
If the engine is worn, has low compression, or the deck is damaged, a single part will not restore reliable performance. A full replacement unit can make more sense in those cases. Weigh the time and effort against the age of the mower.
Good picks for this: BILT HARD 21″ Self Propelled Gas Lawn Mower, Greenworks 40V 16in Push Lawn Mower
Consider Your Lawn Size and Use
A battery push mower suits small lawns with short runtime needs. A gas self-propelled unit handles larger properties and hills better. Match the machine to the square footage and terrain you actually mow.
Good picks for this: Greenworks 40V 16in Push Lawn Mower, BILT HARD 21″ Self Propelled Gas Lawn Mower
Plan for Spare Keys and Storage
Multiple spares reduce the chance of being stranded mid-season. Store a backup in a dry, known location, and never leave a spare key in the mower’s seat area where it can be lost.
Good picks for this: Essential Lawn Mower Start Lever Locking Device 4-Pack, Lawn Mower Start Key for DeWalt Models
Maintain the Engine and Starting Parts
Fresh fuel, a clean air filter and a charged battery prevent many no-start conditions. Owners commonly report that fuel problems and dirty filters cause more trouble than parts failures, so inspect these before replacing components.
Good picks for this: BILT HARD 21″ Self Propelled Gas Lawn Mower, DEWALT 12A-01T9739 Recoil Starter
FAQ
Why won’t my DeWalt self drive lawn mower start even though the key is in?
The key may be worn, not fully seated, or the wrong model. Check that the key engages the switch and compare its number with your model. If the key is fine, the fault may lie in the fuel, spark or starter system.
How do I find my DeWalt model number?
Look for the data plate or label on the deck, near the handle or engine. The model number is usually printed there. Match it exactly against any part listing before ordering.
Can a recoil starter be replaced without special tools?
Many recoil starters are held by a few bolts and can be swapped with basic hand tools. Disconnect the spark plug wire first. If you are unsure, consult a qualified small-engine repair professional.
Is a battery mower a good replacement for a gas self drive mower?
It can be, for smaller lawns with level terrain. Battery mowers avoid fuel and pull-cord problems but may not last as long on a single charge as a gas unit on a large property.
Do I need to replace the fuel before troubleshooting a no-start?
Old or stale fuel is a frequent cause of no-start conditions, especially after storage. Draining and refilling with fresh fuel is a low-cost first step before buying parts.
When should I stop repairing and buy a new mower?
Consider replacement if the engine has low compression, the deck is cracked, or repairs would exceed the value of the mower. A new unit may be more practical in those situations.
Conclusion
For most DeWalt self drive lawn mower won’t start cases, begin with the start key and model-number check, since these are the most common and least expensive fixes. If the rope pulls but the engine will not catch, the recoil starter is the next target. Owners who want to leave gas behind for a small lawn may prefer the battery push mower, while those replacing a failed machine may find the self-propelled gas unit a more complete solution. The spare lock lever pack suits anyone who wants backups on hand.
Sources
- Consumer product safety guidance on powered lawn mowers, including safe starting and blade handling (cpsc.gov)
- Information on outdoor power equipment and the energy and emissions differences between gas and electric lawn tools (energy.gov)
- Workplace and equipment safety guidance on working with powered machinery and fuel handling (osha.gov)
Related reading
- Self Propelled Lawn Mower Won't Start: 8 Causes and Fixes
- John Deere Self Propelled Lawn Mower Won't Start: 7 Fixes to Try First
- DeWalt Lawn Mower Won't Start? 9 Fixes to Try First
- DeWalt Battery Lawn Mower Won't Start? 5 Best Replacement Parts Compared
- DeWalt 20V Lawn Mower Won't Start? 3 Best Parts and Battery Picks
About Graham Fisher
Graham Fisher is part of our editorial team and reviews and edits our lawn mowers guides, checking product details against manufacturer specifications and owner feedback.
