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.
40 fault codes documented· Manitou / JLG / Genie / CAT · Construction + ag + rental fleets
Telehandler Fault Codes
Showing 24 of 40 Telehandler codes across Manitou, JLG, Genie, and CAT, 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.
CAT-TH-100-1 critical
Engine Oil Pressure Below Safe Operating Threshold
CAT-TH-110-0 critical
Engine Coolant Temperature High (Most Severe)
CAT-TH-190-0 critical
Engine Overspeed: Engine Speed Above Limit (Most Severe)
CAT-TH-5246-15 critical unverified
EPA Aftertreatment Inducement Derate Active
GENIE-TH-32-01 critical unverified
Engine Coolant Temperature High Warning
GENIE-TH-33-01 critical unverified
Engine Oil Pressure Below Safe Operating Threshold
JLG-TH-110-0 critical
Engine Coolant Temperature High (Most Severe)
JLG-TH-190-0 critical
Engine Overspeed: Engine Speed Above Limit (Most Severe)
JLG-TH-5246-15 critical unverified
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 (Most Severe)
MANITOU-190-0 critical
Engine Overspeed: Engine Speed Above Limit (Most Severe)
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 unverified
DPF Differential Pressure High, Regen Required
CAT-TH-4364-17 serious unverified
SCR NOx Conversion Efficiency Below Threshold
CAT-TH-639-14 serious unverified
J1939 CAN Bus Off Fault Detected
GENIE-TH-03-01 serious unverified
Frame Tilt Sensor Reads Beyond Safe Operating Angle
GENIE-TH-07-01 serious unverified
TCON Lost CAN Communication With Engine ECM
GENIE-TH-12-01 serious unverified
Boom Lift-Up Disabled, Load Chart Envelope Exceeded
GENIE-TH-14-01 serious unverified
Load Moment Indicator Near Tip-Over Envelope
GENIE-TH-21-01 serious unverified
Steer Angle Sensor Signal Missing or Out of Range
GENIE-TH-99-99 serious unverified
TCON Calibration Data Lost or Invalid
JLG-TH-100-4 serious
Engine Oil Pressure Sensor Circuit Voltage Low (SPN 100 FMI 4)
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. Technical publications are distributed through JLG’s Online Express portal. |
| Genie (Terex) | GTH-636, GTH-844, GTH-1056, GTH-5519 | Genie’s public manual library (manuals.genielift.com) carries Terex-era telehandler manuals; current GTH models were not found there. Fault code formats differ by controller generation. |
| Caterpillar | TH255C, TH3510D, TH514D, TH3510 telehandlers | CAT C3.4 / C7.1 engines. Codes via CAT ET service tool. |
Telehandler Troubleshooting Guides
Step-by-step guides for the problems that stop a machine working, each checked against the manufacturers' own service manuals.
- Load moment indicator (LMI) warning or boom cut-out — What the LMI is protecting against, the wrong-load-table cause, and why the bypass key is not a fix.
- Telehandler won't move or parking brake stuck — The interlocks and switches the manufacturers check, and when a manual brake release is allowed.
- Boom angle sensor fault — What the controller does when it cannot trust the boom angle.
- Boom length or extension sensor fault — Why extend stops and only recovery functions remain.
- Outrigger or stabilizer fault — Why outrigger position switches can stop the machine moving.
- Hydraulic oil temperature warning — Is it the oil or the sender? The manufacturer's quick test.
- Joystick fault or not calibrated — Why functions freeze until the joystick reads neutral.
- DPF light on: stop or keep going? — What the diesel particulate filter warning means on Tier 4 engines.