JLG Telehandler 815 Fault Code: Tilt Sensor - Chassis Tilt Sensor Disagreement
Also called Sensor Error Differential Pressure (DPF); Signal Range Check Low
Tilt Sensor - Chassis Tilt Sensor Disagreement · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault 815 (SPN 3253 / FMI 4) sets when JLG's UGM controller sees a difference between two chassis tilt sensor readings that exceeds its allowed threshold, or logs a DPF sensor signal range low error. On telehandlers with the platform option enabled, this fault blocks platform mode operation until the board is power cycled.
High severity. The machine keeps running but platform mode is locked out, and the fault is described as causing machine system distress. Treat it as a stop-and-diagnose issue before using the platform, since the tilt sensor disagreement is tied directly to platform leveling safety.
What does JLG Telehandler error code 815 mean?
Fault code 815 is logged by the UGM (the machine's control module) when it detects a disagreement between chassis tilt sensor readings, or a low signal range error on a differential pressure sensor (DPF). The two descriptions point to related but distinct sensor-comparison failures that both trigger this same code.
On machines with the platform option enabled, the UGM continuously compares tilt sensor signals to make sure the chassis tilt reading is trustworthy before allowing platform mode. If those readings disagree by more than the allowed amount for the required time, the UGM assumes it cannot trust the tilt data and locks out platform operation as a protective measure.
This is listed as causing machine system distress, meaning the fault is treated seriously by the controller, not just a nuisance code. Because tilt sensing is directly tied to platform stability and leveling, this fault should not be ignored or worked around.
What triggers a JLG Telehandler 815 code?
The platform option must be configured as enabled and the UGM must detect a platform attached. If the UGM detects the machine is driving, the fault sets when there is a 3 degree difference between tilt sensors for 5 seconds. If the UGM detects the machine is not driving, the fault sets when there is a 1 degree difference between tilt sensors for 2 seconds.
Common causes of 815
- Disagreement between two chassis tilt sensor readings beyond the allowed threshold while the platform option is enabled and a platform is attached
- A differential pressure (DPF) sensor signal range check reading low, indicating a sensor circuit or signal problem
- Sensor calibration drift or misalignment between the two tilt sensors
- Wiring or connector faults affecting one tilt sensor's signal while the other reads normally
How to troubleshoot JLG Telehandler 815: first checks
- Confirm whether the machine was driving or stationary when the fault set, since the disagreement threshold and timing differ between those two states
- Inspect tilt sensor wiring and connectors for corrosion, looseness, or damage that could cause one sensor to read incorrectly
- Check that both chassis tilt sensors are securely mounted and undamaged
- Verify the platform is properly attached and recognized by the UGM if platform mode is expected to be available
- Look for any related DPF sensor wiring or connector issues if the differential pressure sensor description applies to your fault log
How the code clears
This fault latches until the controller is power cycled. JLG's documentation notes this may require board replacement, so a simple power cycle may not clear the fault if the underlying tilt sensor disagreement or DPF sensor issue persists. No separate clearing step beyond a power cycle is listed.
Frequently asked questions
What does JLG fault code 815 mean?
It means the UGM controller detected a disagreement between chassis tilt sensor readings, or a low signal range error on a differential pressure sensor. It causes machine system distress and blocks platform mode operation when the platform option is enabled.
Can I still drive the telehandler with fault 815 active?
The fault description does not indicate the machine is disabled from driving, only that platform mode operation is not permitted. Treat any active fault affecting sensor reliability with caution and inspect it before continued use.
Why won't platform mode work after this fault?
The UGM will not permit platform mode operation once fault 815 sets, because it can no longer trust the tilt sensor data needed to safely operate in platform mode.
How do I clear fault code 815?
The fault latches until a power cycle. JLG notes this may require board replacement, meaning a power cycle alone may not resolve it if the tilt sensor disagreement or sensor fault is still present.
What is the difference between the two trigger conditions for this fault?
If the machine is driving, the fault sets after a 3 degree tilt sensor difference lasting 5 seconds. If the machine is not driving, it sets after a smaller 1 degree difference lasting 2 seconds, since a stationary machine should show tighter sensor agreement.
Is fault 815 related to a DPF issue like on diesel engines?
In this context, DPF refers to a differential pressure sensor used in the tilt/platform monitoring system, not the diesel particulate filter used in engine exhaust systems. Don't confuse the two when troubleshooting.