JLG Telescopic Boom Lift 45 Fault Code: Intake Air Temperature (lAT) Sensor Low Voltage
Also called Problems with the S-D CAN based PVG Valves Currently Used on the 1250AJP Only
Intake Air Temperature (lAT) Sensor Low Voltage · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 45 on JLG telescopic boom lifts covers a group of problems with the CAN based PVG (proportional valve group) valves used on the main lift, tower lift, and tower telescope functions, currently applicable only to the 1250AJP. It has a listed priority of 7 and can mean anything from lost CAN communication with a valve to an internal valve fault, wrong wiring, or a bad calibration.
High severity. This code covers many distinct fault conditions tied to the boom's proportional valves. Some are communication glitches, others point to a stuck or obstructed valve spool that can affect boom lift or telescope control. Treat any active code 45 as a reason to stop and inspect before continuing lift operations.
What does JLG Telescopic Boom Lift error code 45 mean?
Fault code 45 is not one single problem. It is a family of related faults reported by the S-D CAN based PVG valves that control the main lift, tower lift, and tower telescope functions on the JLG 1250AJP. The controller assigns this code whenever one of these proportional valves reports an issue over its CAN link.
The specific text logged (main lift PVG communications, tower lift PVG internal fault, main lift PVG valve stuck neutral, and so on) tells you which valve and which failure mode triggered the code. This matters because a lost CAN communications message means something different from a valve reporting its spool is physically stuck extended, retracted, or in neutral.
Other variants point to setup or wiring issues: incorrect valve calibration data, a valve installed in the wrong location, or a power wire run to the wrong valve. These are commissioning or repair-related faults rather than in-service failures, but they will still stop the affected function from working correctly.
Common causes of 45
- Lost CAN communication between the controller and the main lift, tower lift, or tower telescope PVG valve
- Internal fault reported by one of the PVG valves (main lift, tower lift, or tower telescope)
- PVG valve detecting high or low excitation voltage on its own circuit
- PVG valve spool stuck in neutral, extended, or retracted position
- PVG valve spool unable to achieve the commanded position (obstructed)
- Control system sending an invalid or improper command to a PVG valve
- PVG valve not receiving a position command within 250 milliseconds (timeout)
- Incorrect valve setup data requiring a valve calibration
- Incorrect spool parameter data requiring a valve calibration
- PVG valve installed in the wrong location or wired incorrectly during calibration
- Power wire for a PVG valve not connected to the correct valve
- PVG valve sending an unrecognized fault the controller cannot classify
How to troubleshoot JLG Telescopic Boom Lift 45: first checks
- Check the analyzer or display for the exact sub-fault text (which valve: main lift, tower lift, or tower telescope, and which failure mode) since this narrows the repair path immediately
- Inspect the CAN wiring and connectors at the affected PVG valve for corrosion, loose pins, or damage if the fault points to lost communications
- Verify the power wiring to each PVG valve matches the correct valve, especially after any recent valve replacement or wiring work
- Check for signs of a stuck spool by testing whether the affected boom function (lift or telescope) responds at all, responds only in one direction, or is completely unresponsive
- Confirm whether the valve was recently replaced or reinstalled, since location or wiring errors during calibration are a listed cause
- If the fault text calls out a setup or parameter issue, plan for a valve calibration procedure rather than a wiring repair
How the code clears
No separate clearing step is listed. Because several of the sub-faults require a valve calibration (setup fault and parameters incorrect variants) or a wiring correction (location improper and wiring incorrect variants), the fault will likely stay active until the underlying valve issue is physically corrected or the valve is recalibrated.
Frequently asked questions
What does JLG fault code 45 mean?
It is a family of faults related to the CAN based PVG proportional valves controlling main lift, tower lift, and tower telescope functions on the JLG 1250AJP. The exact meaning depends on the specific sub-fault text shown on the display or analyzer, which can range from lost communications to a stuck valve spool or a wiring error.
Does fault code 45 apply to all JLG telescopic boom lifts?
No. This fault is tied to the S-D CAN based PVG valves currently used only on the 1250AJP.
Why won't my boom lift or telescope function move with this code active?
Several sub-faults describe the valve spool being physically stuck in neutral, extended, or retracted, or unable to reach the commanded position at all. Any of these will prevent normal boom movement on the affected function.
Can I fix code 45 by just checking wiring?
Sometimes. If the sub-fault points to wiring incorrect or location improper, correcting the wiring or valve installation may resolve it. But other sub-faults require a full valve calibration, and some point to an internal valve fault that may need valve replacement.
What is a PVG valve calibration and when is it needed?
It is required when the valve's setup data or spool parameter data is incorrect, as reported directly by the valve. This is a listed cause for several code 45 sub-faults and must be performed to clear those conditions.
Is it safe to keep operating with fault code 45 active?
Given that this code can indicate a stuck or obstructed lift or telescope valve, it should be treated seriously. Stop operation of the affected function and diagnose the exact sub-fault before continuing lift work.