Aerial Lift Fault Codes
Scissor lifts, boom lifts, and telehandlers from Genie, JLG, and Skyjack. These are the workhorses of construction sites and rental yards (Sunbelt, United Rentals, Herc, Sunstate). Field techs hit the same codes over and over -- tilt out of level, pothole guard not deployed, joystick not centered, battery low. This hub covers the codes you actually see, with diagnostic steps a rental-yard mechanic can follow with basic tools.
48 fault codes documented· 3 brands (Genie, JLG, Skyjack) · Scissor / boom / telehandler
Most Common Aerial Lift Fault Codes
Showing 30 of 48 Aerial Lifts codes across Genie, JLG, and Skyjack, sorted by severity. Each links to causes, diagnostics, and common fixes.
GENIE-32-01 critical
Engine Coolant Temperature High Warning
GENIE-33-01 critical
Engine Oil Pressure Below Safe Operating Threshold
JLG-100-4 critical
Engine Oil Pressure Below Safe Threshold, Shutdown Triggered
JLG-4351-15 critical
Engine Coolant Temperature Above ECM Warning Threshold
GENIE-03-01 serious
Chassis Tilt Beyond Safe Operating Angle
GENIE-04-01 serious
Pothole Guard Failure to Deploy on Elevation
GENIE-07-01 serious
Engine ECM CAN Communication Lost
GENIE-12-01 serious
Lift Up Cutout Active on Reach Boom
GENIE-14-01 serious
Platform Overload Load Cell Above Rated Capacity
GENIE-21-01 serious
Steer Angle Sensor Signal Missing or Out of Range
GENIE-99-01 serious
Boom Rest Proximity Switch Inconsistent State
GENIE-99-99 serious
Controller Calibration Data Lost or Invalid
JLG-252-12 serious
ECM and ADE Configuration Data Mismatch Detected
JLG-4291-15 serious
Hydraulic Oil Temperature Above Upper Limit
JLG-6017-14 serious
Drive Cutout Active Above Elevation Threshold
JLG-6018-12 serious
Steer Angle Sensor Signal Out of Range
JLG-6019-12 serious
Drive Joystick Calibration Data Lost or Invalid
JLG-6028-12 serious
Chassis Tilt Sensor Angle Outside Safe Envelope
JLG-6029-15 serious
LSS Platform Overload Detected, All Functions Cut
JLG-6056-14 serious
Pothole Guard Deployment Failure Detected
JLG-6058-14 serious
Lift Up Disabled, Platform Load Exceeds Capacity Envelope
JLG-9999-14 serious
Multiple Active Fault Codes Detected by ADE
SKYJACK-12 serious
Chassis Tilt Sensor Out of Safe Range
SKYJACK-13 serious
Pothole Guard Fault, Deploy Failure Detected
SKYJACK-31 serious
Drive Cutout Active, Platform Motion Blocked
SKYJACK-32 serious
Lift Function Cutout Active
SKYJACK-51 serious
Platform Overload Rated Capacity Exceeded
SKYJACK-71 serious
ECM Communication Lost on CAN Network
SKYJACK-81 serious
Hydraulic System Pressure Out of Range
SKYJACK-99 serious
Controller Calibration Data Invalid or Missing
Aerial Lift Brands
| Brand | Applications | Notes |
|---|---|---|
| Genie (Terex) | GS-series electric scissor lifts, S-series straight booms, Z-series articulating booms, GTH telehandlers | GCON / TCON controllers display fault codes in "GG.SS" group.subgroup format. Read deeper detail with the Genie Service Tool laptop software. |
| JLG (Oshkosh) | 600S / 800S / 1200S boom lifts, E450AJ articulating boom, ES / RS scissor lifts, G5/G10 telehandlers | ADE controller displays SPN/FMI codes (e.g. 437/12). JLG Analyzer plugs into the ground controls for full DTC reads and calibrations. |
| Skyjack | SJIII electric scissor lifts, SJ rough-terrain scissors, SJ-46/66/86 boom lifts, SJ telehandlers | Two-digit numeric codes on platform display. Simple analog-style controllers; EZcal handheld for calibrations and code reads. |
Common Aerial Lift Issues
- Battery voltage low (Genie 02-01, JLG 437-12, Skyjack 21) -- charger fault or worn battery pack on rental fleet
- Tilt out of level (Genie 03-01, JLG 6028-12, Skyjack 12) -- chassis on slope, tilt switch bumped during transport
- Pothole guard not deployed (Genie 04-01, JLG 6056-14, Skyjack 13) -- limit switch out of adjustment after transport
- Joystick out of center at power up (Genie 06-01, JLG 6088-14, Skyjack 41) -- common after a hard impact while keyed on
- Calibration required (Genie 99-99, JLG 6019-12, Skyjack 99) -- controller swap, low battery, or firmware update
- Engine ECM no comm on diesel boom lifts (Genie 07-01, JLG 252-12, Skyjack 71) -- bad CAN harness or ECM / controller swap
- Platform overload (Genie 14-01, JLG 6029-15, Skyjack 51) -- LSS sensor calibration drift or actually overloaded