Telehandler Fault Codes
Telehandlers (variable-reach forklifts) bridge construction, agriculture, and rental fleets. Manitou is the global market leader with the MT, MLT, MRT, and MHT lines. JLG, Genie, and Caterpillar all field competitive lines used heavily by Sunbelt, United, Herc and ag dealer fleets. Most codes you see are Tier 4 Final aftertreatment faults (DPF / DEF), boom geometry sensor issues, and load-stability cutouts. This hub now covers all four major brands.
64 fault codes documented· Manitou / JLG / Genie / CAT · Construction + ag + rental fleets
Most Common Telehandler Fault Codes
Showing 24 of 64 Telehandler codes across Manitou, JLG, Genie, and CAT, sorted by severity. Each links to causes, diagnostics, and common fixes.
CAT-TH-100-1 critical
Engine Oil Pressure Below Safe Operating Threshold
CAT-TH-110-0 critical
Engine Coolant Temperature High Shutdown Fault
CAT-TH-190-0 critical
Engine Overspeed Shutdown: RPM Exceeded Safe Limit
CAT-TH-5246-15 critical
EPA Aftertreatment Inducement Derate Active
GENIE-TH-32-01 critical
Engine Coolant Temperature High Warning
GENIE-TH-33-01 critical
Engine Oil Pressure Below Safe Operating Threshold
JLG-TH-100-4 critical
Engine Oil Pressure Below Safe Threshold, ECM Shutdown
JLG-TH-110-0 critical
Engine Coolant Temperature High Shutdown
JLG-TH-190-0 critical
Engine Overspeed Shutdown, ECM Cut Fuel
JLG-TH-5246-15 critical
EPA Aftertreatment Inducement Severe Derate Active
MANITOU-100-1 critical
Engine Oil Pressure Below Safe Operating Threshold
MANITOU-110-0 critical
Engine Coolant Temperature High Shutdown
MANITOU-190-0 critical
Engine Overspeed Shutdown RPM Limit Exceeded
CAT-TH-100-3 serious
Oil Pressure Sensor Signal Voltage Too High
CAT-TH-190-8 serious
Engine Speed Sensor Signal Erratic or Abnormal
CAT-TH-3251-15 serious
DPF Differential Pressure High, Regen Required
CAT-TH-4364-17 serious
SCR NOx Conversion Efficiency Below Threshold
CAT-TH-639-14 serious
J1939 CAN Bus Off Fault Detected
CAT-TH-BOOM-ANGLE-OUT-OF-RANGE serious
Boom Angle Sensor Signal Out of Range
CAT-TH-BOOM-EXTENSION-FAULT serious
Boom Extension Sensor Signal Abnormal
CAT-TH-FRAME-LEVEL-FAULT serious
Frame Tilt Sensor Out of Range, Auto-Level Disabled
CAT-TH-HYDRAULIC-OIL-TEMP-HIGH serious
Hydraulic Oil Temperature Above Safe Operating Limit
CAT-TH-LOAD-MOMENT-EXCEEDED serious
Load Moment Limit Exceeded, Boom Functions Cut Out
GENIE-TH-03-01 serious
Frame Tilt Sensor Reads Beyond Safe Operating Angle
Telehandler Brands
| Brand | Applications | Notes |
|---|---|---|
| Manitou | MT 1840 / 1740 SLT (telehandler), MLT 737 / 960 (ag telehandler), MRT 2150 (rotating), MHT 10130 (heavy-duty) | Global market leader. Engines vary by model: Kubota, Perkins, John Deere, or CAT. Manitou diagnostic software (Interactive View on post-2017 machines, Plug & Diag OpenPAD on 2001-2017 machines, or Jaltest) for diagnostics. |
| JLG | G5-18A, G10-55A, G12-55A, 1644 | Oshkosh-owned. Shares ADE controller architecture with JLG boom lifts. JLG Analyzer for code reads. |
| Genie (Terex) | GTH-636, GTH-844, GTH-1056, GTH-5519 | TCON controller. Codes follow the same group.subgroup format as Genie scissor and boom lifts. |
| Caterpillar | TH255C, TH3510D, TH514D, TH3510 telehandlers | CAT C3.4 / C7.1 engines. Codes via CAT ET service tool. |
Common Telehandler Issues
- Boom angle / extension sensor faults (BOOM-ANGLE-SENSOR, BOOM-EXT-LIMIT) -- after sensor swap or controller reflash
- Load Stability Indicator active (LSI-ACTIVE) -- approaching tip-over envelope, operational warning
- Outrigger not deployed (OUTRIGGER-NOT-DEPLOYED) -- limit switches dirty or pin sensor failed
- Hydraulic oil temperature high (HYD-OIL-TEMP-HIGH) -- sustained loader work in hot weather
- DPF differential pressure high (3251-15) -- after extended low-load idle on Tier 4 Final units
- DEF tank level low (1761-1) -- dryout in long idle periods
- Joystick calibration required (JOYSTICK-CALIBRATION) -- post-controller-swap or low-battery event