Understanding OTIS GOEC escalator fault codes helps maintenance technicians identify abnormal operating conditions and narrow down the possible causes. The Service Tool and Operation / Control Panel display fault information that can guide further inspection of the electrical, mechanical, and safety systems.
This guide covers fault conditions 14–23, including motor underspeed, low lubricant level, direction detection errors, DC power supply faults, handrail slippage, missing run signals, safety fuse faults, and main drive chain failure.
Important: This article is just for reference. Actual fault diagnosis and reset procedures should follow the applicable equipment manual and site safety requirements.
14. Motor Underspeed Detection
Fault Code Display
Service Tool: 0119 NRD down US
Operation / Control Panel: OTIS US
Possible Cause
During downward operation, the escalator speed suddenly decreases or the escalator stops. After detecting the underspeed signal, the ECB board stops the escalator.
Troubleshooting
1. Check that the main motor power cables are connected correctly and inspect for wiring faults.
2. Inspect the motor speed detection sensor and replace it if damaged.
15. Oil Level Fault Detection
Fault Code Display
Service Tool: 0120 Oillack S44
Operation / Control Panel: OTIS S44
Possible Cause
The lubricant level in the oil reservoir has fallen to the warning level.
Troubleshooting
1. Add sufficient lubricant to the oil reservoir.
2. If the warning remains after the reservoir has been filled, check whether the ST2 board (RS4R) is operating normally.
3. Check the ECB parameter settings.
4. Check the magnetic float switch. The supplied reference recommends reversing the magnetic float’s installation orientation to reverse its polarity.
Any float-switch adjustment should be verified against the applicable equipment documentation before implementation.
16. KSU and D Relay or KSD and U Relay Detection
Fault Code Display
Service Tool: 0121 KS_Wire E15
Operation / Control Panel: OTIS E15
Possible Cause
A fault in the key-switch or inspection-box wiring may cause the actual escalator travel direction to differ from the direction detected by the ECB.
Troubleshooting
Inspect the wiring connections on the ECB board, key switch, and inspection box. Identify and correct any wiring faults before returning the escalator to service.
17. DC Power Supply Fault Detection
Fault Code Display
Service Tool: 0122 Pfail E16
Operation / Control Panel: OTIS E16
Possible Cause
An ECB board fault or unstable supply voltage may cause abnormal operation of the VCON, VRS, or 5 V DC circuits on the PC board.
Troubleshooting
1. Check whether the main supply voltage is too low and verify that the voltage is stable.
2. Check the power supply to transformers T1 and T9.
If the fault persists and the ECB board is confirmed to be defective, replace the board in accordance with the applicable service procedure.
18. KSU/D Activation Longer Than 10 Seconds
Fault Code Display
Service Tool: 0123 KS_>10s E17
Operation / Control Panel: OTIS E17
Possible Causes
The operating key switch is held in the start position for more than 10 seconds.
An internal short circuit exists in the key-switch wiring.
Water ingress has caused a short circuit inside the key switch.
Troubleshooting
1. Operate the start key switch for approximately 1–2 seconds, as indicated in the supplied reference.
2. Inspect the key-switch wiring and correct any electrical faults.
If the warning persists, investigate the switch and its circuit before attempting another start.
19. Handrail Slippage Detection
Fault Code Display
The displayed codes vary according to the affected handrail and whether the escalator has been software-locked.
|
Condition |
Service Tool Display |
Operation / Control Panel |
| Right handrail slippage | 0124 HRS right B9 | OTIS B9(E18) |
| Left handrail slippage | 0125 HRS left B8 | OTIS B8(E19) |
| Right handrail slippage with software lock | 0126 HRSlock E20 | OTIS E20 |
| Left handrail slippage with software lock | 0127 HRSlock E21 | OTIS E21 |
Possible Causes
The friction wheel and roller chain in the handrail drive cannot maintain sufficient pressure on the handrail.
The handrail-related parameters on the ECB board are incorrectly configured.
Troubleshooting
1. Inspect the handrail drive and roller-chain tensioning mechanism.
2. Adjust the tensioning spring as specified by the equipment documentation so that the roller chain and friction wheel apply the required pressure to the handrail.
3. Check and correct the handrail-related ECB parameters if necessary.
4. If the system has entered a software lock, use the prescribed reset procedure after the underlying fault has been corrected.
Do not reset the escalator before identifying and resolving the cause of the slippage.
20. No Run Signal Two Seconds After Starting
Fault Code Display
Service Tool: 0128 No RUN E22
Operation / Control Panel: OTIS E22
Possible Cause
Relays K3, K4, or K15 fail to operate correctly after the escalator starts.
Troubleshooting
1. Inspect relays K3, K4, and K15. Replace any confirmed defective relay.
2. Check whether contacts K43 and K44 operate correctly.
3. Inspect the wiring connections.
21. Escalator Continues Running in the Stop State
Fault Code Display
Service Tool: 0131 RUN on E25
Operation / Control Panel: OTIS E25
Possible Causes
Contacts in contactor K3, K4, or K15 are stuck closed.
Auxiliary contacts of K3, K4, or K15 are stuck closed.
ECB terminals P9:3 and P9:2 are short-circuited.
Troubleshooting
1. Inspect the relevant contactors and replace defective units.
2. Check the wiring and connections.
3. Verify that the cause has been eliminated before returning the escalator to operation.
Unexpected movement during a stop command requires immediate attention. Isolate the equipment and follow the applicable safety procedures before inspecting electrical components.
22. Safety Circuit Fuse Fault Detection
Fault Code Display
The reference lists the following displays:
Service Tool: 0161 Drv FSA GR3 for 6 Group; 0132 Sa.fuse FSA for 30 Fault.
Operation / Control Panel: OTIS GR3 for 6 Group; OTIS F26 for 30 Fault.
Possible Cause
A short circuit in the ECB board hardware or associated wiring may cause excessive current, resulting in a blown fuse on the ECB board.
Troubleshooting
1. Inspect the ECB board and associated wiring for short circuits.
2. Identify and correct the underlying fault.
3. Replace the fuse only after the cause has been addressed, using the specified fuse rating and the applicable service procedure.
23. Main Drive Chain Breakage Detection
Fault Code Display
The reference lists the following displays:
Service Tool: 0162 Drv S28 GR3 for 6 Group; 0133 BDC S28 for 30 Fault.
Operation / Control Panel: OTIS GR3 for 6 Group; OTIS S28 for 30 Fault.
Possible Cause
When the main drive chain breaks, chain tension drops sharply. The associated sliding shoe can move because the pressure acting on it is lost. This movement activates the connected safety switch, and the ECB board stops the escalator.
Troubleshooting
1. Replace the damaged drive chain.
2. Adjust the relative positions and clearances of the drive chain, sliding shoe, and safety switch according to the equipment specifications.
3. Verify the safety-switch operation and the relevant mechanical clearances before returning the escalator to service.
For accurate diagnosis, always refer to the equipment-specific documentation and approved service procedures.
Post time: Oct-28-2026