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
Aerial Lift Fault Codes
Showing 30 of 48 Aerial Lifts codes across Genie, JLG, and Skyjack, sorted by severity. Codes marked unverified could not be confirmed against freely available manufacturer documentation; treat their meanings as unconfirmed. Each links to causes, diagnostics, and common fixes.
GENIE-32-01 critical unverified
Engine Coolant Temperature High Warning
GENIE-33-01 critical unverified
Engine Oil Pressure Below Safe Operating Threshold
JLG-4351-15 critical unverified
Engine Coolant Temperature Above ECM Warning Threshold
GENIE-03-01 serious unverified
Chassis Tilt Beyond Safe Operating Angle
GENIE-04-01 serious unverified
Pothole Guard Failure to Deploy on Elevation
GENIE-07-01 serious unverified
Engine ECM CAN Communication Lost
GENIE-12-01 serious unverified
Lift Up Cutout Active on Reach Boom
GENIE-14-01 serious unverified
Platform Overload Load Cell Above Rated Capacity
GENIE-21-01 serious unverified
Steer Angle Sensor Signal Missing or Out of Range
GENIE-99-01 serious unverified
Boom Rest Proximity Switch Inconsistent State
GENIE-99-99 serious unverified
Controller Calibration Data Lost or Invalid
JLG-100-4 serious
Engine Oil Pressure Sensor Circuit Voltage Low (SPN 100 FMI 4)
JLG-252-12 serious unverified
ECM and ADE Configuration Data Mismatch Detected
JLG-4291-15 serious unverified
Hydraulic Oil Temperature Above Upper Limit
JLG-6017-14 serious unverified
Drive Cutout Active Above Elevation Threshold
JLG-6018-12 serious unverified
Steer Angle Sensor Signal Out of Range
JLG-6019-12 serious unverified
Drive Joystick Calibration Data Lost or Invalid
JLG-6028-12 serious unverified
Chassis Tilt Sensor Angle Outside Safe Envelope
JLG-6029-15 serious unverified
LSS Platform Overload Detected, All Functions Cut
JLG-6056-14 serious unverified
Pothole Guard Deployment Failure Detected
JLG-6058-14 serious unverified
Lift Up Disabled, Platform Load Exceeds Capacity Envelope
JLG-9999-14 serious unverified
Multiple Active Fault Codes Detected by ADE
SKYJACK-12 serious unverified
Chassis Tilt Sensor Out of Safe Range
SKYJACK-13 serious unverified
Pothole Guard Fault, Deploy Failure Detected
SKYJACK-31 serious unverified
Drive Cutout Active, Platform Motion Blocked
SKYJACK-32 serious unverified
Lift Function Cutout Active
SKYJACK-51 serious unverified
Platform Overload Rated Capacity Exceeded
SKYJACK-71 serious unverified
ECM Communication Lost on CAN Network
SKYJACK-81 serious unverified
Hydraulic System Pressure Out of Range
SKYJACK-99 serious unverified
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 | Fault code format depends on the controller generation: current machines report an error source and error type (on the Z-60 DC, source 24 is the primary boom angle sensor), and GCON slab scissors show alphanumeric codes such as H001 on the ground-control screen. Genie publishes service, parts and operator manuals free at manuals.genielift.com, listed by model and serial number. |
| JLG (Oshkosh) | 600S / 800S / 1200S boom lifts, E450AJ articulating boom, ES / RS scissor lifts, G5/G10 telehandlers | Technical publications are distributed through JLG’s Online Express portal. Engine faults from J1939 diesel engines are reported as SPN/FMI pairs. |
| Skyjack | SJIII electric scissor lifts, SJ rough-terrain scissors, SJ-46/66/86 boom lifts, SJ telehandlers | Skyjack publishes operator, service and parts manuals at techpub.skyjack.com, looked up by model and serial number. |
Aerial Lift Troubleshooting Guides
Step-by-step guides for the problems that stop a machine working, each checked against the manufacturers' own service manuals.
- Tilt alarm or level sensor fault — Why lift and drive stop on a slope, and how to tell a real slope from a sensor problem.
- Emergency stop circuit fault — Why nothing works: the E-stop buttons to check first, then the wiring.
- Joystick fault or not calibrated — Why drive or boom functions freeze, including the joystick-held-at-start-up cause.
- Boom angle sensor fault — Why a boom lift crawls along with the boom down, and why calibration is a safety step.
- Boom length or extension sensor fault — Why the boom will retract but not extend, and the cross-check the controller runs.
- Outrigger or stabilizer fault — Limit switches and coils that stop lift or drive when outrigger position is not confirmed.