The Sun Joe MJ403E is a 13-amp corded electric walk-behind lawn mower + mulcher designed for small to mid-sized lawns. Its 17-inch steel blade, 7-position cutting-height adjustment, 12-gallon grass collection bag, and removable mulch plug support straightforward mowing and mulching without gas or oil.
MJ403E
electric
cutting width
bag + mulch
Product Gallery
Why It Stands Out
17-inch cutting path
The 13-amp motor powers a 17-inch steel blade for efficient mowing across small to mid-sized lawns.
Bag or mulch
Use the 12-gallon rear collection bag for mowing, or remove the bag and insert the mulch plug to recycle clippings back into the lawn.
Seven cutting heights
Adjust the mower from 0.98 to 2.87 inches using the 7-position height adjustment lever.
12-gallon collection bag
The rear grass collection bag includes an indicator window that shows when airflow is restricted and the bag is ready to be emptied.
Technical Specifications
| Model | MJ403E |
|---|---|
| Product type | Corded electric lawn mower + mulcher |
| Motor | 13 amp |
| Rated voltage | 120V ~ 60 Hz |
| No-load speed | 3,500 RPM |
| Blade | 17 in. (43 cm) steel blade |
| Cutting width | 17 in. (43 cm) |
| Cutting-height range | 0.98–2.87 in. (25–73 mm) |
| Height adjustment | 7-position manual adjustment |
| Cutting options | Bagging + mulching |
| Grass-bag capacity | 12 gal. (45 L) |
| Wheel size | Front: 6.5 in. (16.5 cm); rear: 10 in. (25.4 cm) |
| Drive system | Manual push / walk-behind |
| Maximum extension-cord length | 100 ft. (30 m) |
| Extension-cord gauge | Up to 50 ft.: 14 AWG; over 50 ft. to 100 ft.: 12 AWG |
| Net weight | 31.5 lb. (14.3 kg) |
| Gross weight | 36.5 lb. |
| Assembled dimensions | 55.1 in. D × 19.7 in. W × 43.3 in. H |
| Sound power level | 92 dB |
| Warranty | 2 years |
| Manual | Download the MJ403E operator's manual |
What’s in the Box
- MJ403E electric lawn mower + mulcher body
- Upper handle frame
- Lower handle frame
- Grass collection bag
- Mulch plug, preassembled on the mower body
- Two upper-handle knob-and-bolt sets
- Two lower-handle knob-and-bolt sets
- Two cable clips
- Grass collection bag handle
- Operator’s manual and registration card
Safety Before Mowing
- Do not use the mower in rain or when the grass is damp or wet.
- Wear eye protection and substantial protective footwear.
- Remove rocks, wire, toys, sticks, and other foreign objects from the mowing area.
- Keep children, bystanders, and pets a safe distance away.
- Do not operate without the grass catcher, guards, or other safety devices properly installed and working.
Extension Cord Requirements
| Cord Length | Minimum Wire Gauge |
|---|---|
| Up to 50 ft. (15 m) | 14 AWG |
| Over 50 ft. to 100 ft. (15–30 m) | 12 AWG |
Assembly
-
Attach the lower handle
Secure the lower handle frame to the mower with the two lower-handle knobs and bolts. Tighten both sides securely.
-
Attach the upper handle
Slide the extension-cord restraint hook onto the upper handle frame, then connect the upper handle to the lower handle using the two upper-handle knobs and bolts.
-
Secure the power cord
Use the two supplied cable clips to secure the power cord along the lower handle frame.
-
Fit the grass collection bag for bagging
Lift the grass collection bag cover, remove the preinstalled mulch plug, and mount the assembled grass collection bag securely.
Choose Bagging or Mulching
| Mode | Setup |
|---|---|
| Bagging | Lift the rear grass collection bag cover, remove the mulch plug, and install the grass collection bag securely. |
| Mulching | Lift the grass collection bag cover, remove the grass collection bag, insert the mulch plug, and close the cover. |
Adjust the Cutting Height
| Position | Cutting Height |
|---|---|
| 1 | 0.98 in. (25 mm) |
| 2 | 1.18 in. (30 mm) |
| 3 | 1.50 in. (38 mm) |
| 4 | 1.89 in. (48 mm) |
| 5 | 2.17 in. (55 mm) |
| 6 | 2.56 in. (65 mm) |
| 7 | 2.87 in. (73 mm) |
Start and Stop the Mower
-
Secure the extension cord
Push a loop of the extension cord through the restraint hook and connect the mower’s appliance cord to a suitable outdoor extension cord.
-
Start on short grass
Do not start the mower in tall grass. Position the cord safely on a footpath or previously mowed area.
-
Use the safety-start sequence
Press and hold the safety-lock button while pulling the switch-bar lever toward the handle. Once the mower starts, release the safety-lock button while continuing to hold the switch-bar lever.
-
Stop the mower
Release the switch-bar lever. The blade continues rotating briefly, so wait until it comes to a complete stop before touching the underside of the mower.
Grass Collection Bag Indicator
- When the bag is empty or not yet full, the grass indicator window remains open or flutters with airflow.
- When the bag reaches maximum capacity, the indicator window remains closed because airflow is restricted. Empty the bag before continuing.
Mowing + Mulching Tips
- Mow only in dry conditions.
- Keep the extension cord behind you and on the already-cut portion of the lawn.
- Reduce walking speed in thick grass for a cleaner cut and better clipping discharge.
- For a healthy lawn, remove one-third or less of the total grass length at a time.
- Use the highest cutting position on uneven ground or in tall weeds.
- For effective mulching, do not mulch wet grass because clippings can stick to the underside of the deck.
Maintenance and Storage
-
Disconnect power
Unplug the mower and make sure all moving parts have stopped before cleaning, inspection, or service.
-
Keep the mower clean
Remove grass, leaves, and accumulated debris, especially around the motor and discharge path.
-
Inspect the blade and hardware
Keep the mower blade sharp and clean. Check nuts, bolts, screws, and safety devices regularly.
-
Store indoors
Keep the mower in a dry, clean, cool area out of the reach of children and away from corrosive materials such as fertilizer and rock salt.
-
Fold the handles if needed
The upper and lower handles can be folded for compact storage. Avoid bending or kinking the power cord.
Blade Care and Replacement
-
Disconnect the mower
Unplug the mower before beginning any blade work.
-
Expose the blade
Turn the mower onto its side to access the underside of the blade housing.
-
Remove the blade
Grip the blade with a cloth or heavy-duty gloves. Use an adjustable wrench to turn the blade bolt counterclockwise and carefully remove the blade.
-
Install the replacement
Fit the new blade and bolt back in place by reversing the removal steps. The manual advises having the blade resharpened or replaced by an authorized service center.
Troubleshooting
The motor does not run
Check: Mains connection, circuit breaker or fuse, whether the mower is being started in tall grass, and whether the discharge channel or housing is blocked.
Try: Confirm the power connection, start on short or previously mowed grass, and clean the discharge path only while the mower is unplugged.
Motor power drops
Check: Cutting height and whether the discharge channel or housing is restricted.
Try: Correct the cutting height and clean the discharge path with the mower unplugged.
The grass collection bag does not fill sufficiently
Check: Cutting height, wet grass, blocked discharge path, and blade condition.
Try: Correct the cutting height, allow the lawn to dry, clean the discharge path, and have the blade resharpened or replaced if necessary.
Replacement Accessories
| Accessory | Model |
|---|---|
| 17-inch replacement mower blade | MJ403E-32 |
| Grass collection bag for MJ403E | MJ403E-25 |
| Power Joe SJTW-A 14-gauge, 50-foot outdoor extension cord with lighted end | PJEXT50-B |
Frequently Asked Questions
What comes with the MJ403E?
The manual lists the mower body, upper and lower handle frames, grass collection bag, preinstalled mulch plug, upper- and lower-handle hardware, two cable clips, grass collection bag handle, and manual with registration card.
Is the MJ403E gas-powered or electric?
It is a 13-amp corded electric mower + mulcher.
What lawn size is it designed for?
The Shop Joe product page identifies it for small to mid-sized lawns and lists a yard-size range of 1/4 to 1/2 acre.
Can it bag and mulch?
Yes. Use the rear grass collection bag for bagging or remove the bag and install the mulch plug for mulching.
Which extension cord should I use?
The manual specifies 14 AWG for cords up to 50 ft. and 12 AWG for cords over 50 ft. up to 100 ft. Do not use an extension cord longer than 100 ft.
Can I mow wet grass?
No. The manual says not to use the mower in rain or when grass is damp or wet.
What cutting heights are available?
Seven positions provide cutting heights from 0.98 to 2.87 inches (25–73 mm).
Which replacement blade fits?
The operator’s manual identifies replacement blade MJ403E-32.
What warranty applies?
The current Shop Joe product page lists a 2-year warranty.