Hiboy S2, S2 Pro and KS4: display to controller communication error (E3, or E1 on the S2 Lite)

The display lights up but shows E3 (or E1 on an S2 Lite), and the scooter won't ride normally. Hiboy's troubleshooting guide lists E3 as a communication problem between the display and the controller on the S2, S2 Pro, S2 MAX, S2R, S2R Plus, KS4, KS4 Pro and MAX Pro. On the S2 Lite the same fault is E1 (Hiboy troubleshooting guide). The short answer: the cable between the handlebar and the deck is the usual suspect, then the display, and only then the controller.

Most likely cause

The display and the controller talk over a cable that runs down the stem, past the folding joint, to the deck. For E3, Hiboy's fix is to replace the display to controller cable, the display board and the controller. For the S2 Lite's E1, Hiboy says to check the direct connection between display and controller first and fix it if loose, and only then replace the cable, display board and controller (Hiboy troubleshooting guide). Because the cable is the cheapest of the three and the part that flexes every time you fold, it makes sense to start there.

Other causes to rule out

• A blank or dead display: Hiboy's won't turn on guide suggests inspecting the display wiring harness, and only then suspecting the display itself.
• Low battery or a charging problem: E5 is low voltage on the same models. See Hiboy E5 low voltage.
• Water: a wet connector can interrupt signals. See e-bike got wet; the drying advice applies to scooters too.

How to confirm

1. Power off, wait a few seconds, power on and read the code again.
2. Unfold and refold the stem slowly with the scooter on. If the code comes and goes as the stem moves, the cable is pinched or broken near the fold.
3. Look along the cable at the handlebar and the folding joint for crushing, rubbing through, or a cable pulled tight.
4. On the S2 Lite, follow Hiboy's step of checking the direct connection between display and controller. If you can reach it without opening the controller, make sure it is fully pushed home. See inspect and clean connectors.
5. Note whether the code appears every time or only in wet weather. Tell the shop either way.

Fix options

Reseat the display connection (easy)

Hiboy's first step on the S2 Lite. With the power off, unplug and firmly replug the connector you can reach, checking for bent pins or moisture.

Replace the display to controller cable (moderate)

Hiboy sells a display controller cable for the S2, S2 Pro and S2 Nova. The product page links two step by step videos from Hiboy. The cable runs through the stem, so take photos of the routing before you pull the old one. The part can't be returned, so check fit with Hiboy first.

Replace the display (easy to moderate)

Hiboy sells a display for the S2 and S2 Pro in two versions and asks you to contact support with your serial number if unsure which you need. Its S2 series parts page also lists displays for the S2 Lite and S2 MAX.

Replace the controller (pro)

If a new cable and display don't clear the code, the controller is next in Hiboy's list. The parts page lists an older S2 controller only, so ask Hiboy support for other models. Have a shop fit it, because the controller connects to the battery and motor.

Parts

• Display to controller cable (Hiboy part)
• Display (Hiboy part, match the version)
• Controller (through Hiboy support)

When to get a pro

Get help if the cable is damaged inside the deck, if the code persists after a new cable and display, or if you see scorching on any connector. See display blank or flickering and when to call a pro.

Sources

• Hiboy troubleshooting guide, hiboy.com
• won't turn on guide, hiboy.com
• display controller cable for the S2, S2 Pro and S2 Nova, hiboy.com
• display for the S2 and S2 Pro, hiboy.com
• S2 series parts page, hiboy.com

Stuck after these checks? Find a shop near you.