What to check first
Find the two small sensor units on or near the gate posts, usually facing each other at bumper height. Wipe both lenses clean and check nothing — a branch, a bicycle, a planter — sits between them. A blocked or dirty beam is the most common cause and the easiest to rule out first.
Test the remote against the manual switch or keypad if you have one. If manual works but the remote does not, the fault is the remote and receiver, not the sensor or motor.
Note exactly what the gate does: does it not move, stop partway, reverse unexpectedly, or blink a light pattern? That detail helps a provider guess the fault before arriving.
Most auto-gates also keep a manual bolt as a backup if the motor fails. If that mechanical latch is what's stuck, not the motor, HDB's home-care guidance on fixing gate bolts that "cannot slot or retract properly" is the more relevant starting point than a sensor check.
The likely causes, in order
A misaligned or blocked beam (most common). The most common cause is the infrared safety beam out of alignment or blocked, whether by a knock, a plant that has grown into the beam path, rain on the lens, or dirt built up on the sensor eyes. The gate's control unit is designed to refuse to move whenever it cannot confirm the beam is clear, since that beam is what stops the gate closing on a person or a car. Check: clean both lenses and clear the path between them, then try the gate again.
The remote and receiver out of sync. The second cause is the remote and receiver losing sync, often after a power outage, a battery change, or simply after years of use as the rolling code drifts. This shows up as the gate not responding to the remote at all while the manual or keypad control still works normally. Check: does the manual switch move the gate when the remote does not?
A motor fault or safety stop. The third cause is the motor unit's own fault condition: an obstruction it detected on a previous cycle, a worn limit switch, or a power supply issue at the motor itself, which the system treats as a safety stop rather than a normal open or close. This is the cause most likely to need a technician rather than a homeowner fix. Check: does neither the remote nor the manual control move the gate at all?
When to call, and who
Stop and call now if the gate will not close and is your only secure entrance, or if it moves unpredictably with people nearby. SPF's own housebreaking advisory names a secure gate as a basic deterrent to unauthorised entry, and a gate stuck open removes that deterrent entirely until it is fixed.
The reverse fault is urgent too. If the gate is stuck fully closed and will not open by any means, not just the automatic mode, SCDF's fire safety guidance requires escape routes to stay clear of obstruction — and a gate blocking your own way out fails that standard until it's fixed.
Realign or clean the sensor eyes yourself first if the gate opens and closes fine on manual but only refuses automatic mode — often a quick beam fix. Call a provider if the gate will not open or close at all, or moves erratically, since that points to the motor.
Do not open the motor unit or its wiring yourself. Auto gate motors run on mains power, and opening the casing on a live unit is electrical work, not gate work — that is for a provider or a Licensed Electrical Worker, not a homeowner fix.
What it costs
Ask two or three for a written quote instead.
When you ask, describe exactly what the gate does (does not move, moves erratically, responds to manual but not remote), the motor brand if known, and whether the fault is new or recurring. Ask whether the quote covers diagnosis only, and whether a replacement part is priced separately from labour.
Who to call, and how to judge them
A provider checks the beam alignment and power to the sensor first, then the remote and receiver sync, then the motor's own fault log, before quoting. Ask them to say which of the three it is rather than a single price for "sensor repair."
Auto gate repair is not licensed work in Singapore, so there is no public register to check. Judge a provider on a written scope, a stated call-out fee and a business you can verify instead. An ACRA registration confirms the business exists, nothing more.
Frequently asked questions
Why has my auto gate suddenly stopped opening on its own?
An auto gate sensor fault is usually a misaligned or blocked infrared beam, a remote or receiver losing sync, or the motor's own safety sensor tripping and refusing to move the gate. Checking the beam first rules out the easiest and most common cause.
Is a gate stuck open a security problem, not just an inconvenience?
Yes. SPF's own housebreaking advisory names a secure gate as a basic deterrent to unauthorised entry, and a gate stuck open removes that deterrent entirely until it is fixed.
Can I fix the sensor myself, or do I need to call someone?
Realign or clean the sensor eyes yourself first if the gate opens and closes fine on the remote or manual switch but only refuses the automatic mode. Do not open the motor unit or its wiring yourself — that is electrical work for a provider, not a homeowner fix.
Sources
- SPF, "Housebreaking" advisory (fetched 15 Sep 2026)
- HDB, "Gate and Door" home care guide (fetched 15 Sep 2026)
- SCDF, "Fire Safety Guidelines for Residential Estate" (fetched 15 Sep 2026)
- EMA, "Engaging Licensed Workers" (fetched 15 Sep 2026, confirmed live regulator page; cited as a pointer only, page did not render body text)
Compare gate and grille repair providers and describe exactly what the gate does before you book.
