JLG Articulating Boom Lift 87 Fault Code: Atmospheric Pressure
Also called New Main Angle 1 Sensor Detected, New Main Angle 2 Sensor Detected, New Main Angle Sensors
Atmospheric Pressure · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Code 87 on JLG articulating boom lifts corresponds to SPN 108 / FMI 12 and covers two different situations depending on the message shown: an atmospheric pressure reading outside the permissible range on the control unit hardware, or (on 1250AJP models only) detection of a new main angle 1 or main angle 2 sensor that does not match the sensor the system was calibrated with.
Medium severity. This is a control unit hardware and sensor-identity fault, not an active hydraulic or engine failure. The atmospheric pressure version often clears itself once conditions return to normal range, but a new-sensor detection on the 1250AJP means the boom angle calibration is no longer trustworthy until it is addressed, which affects lift accuracy and safety systems.
What does JLG Articulating Boom Lift error code 87 mean?
Fault code 87 (SPN 108 / FMI 12) actually reports two unrelated conditions depending on which text the display shows. The first is an atmospheric pressure fault: the control unit's internal pressure monitoring detected a reading outside its permissible range. This is described as a fault message that disappears once the pressure sensed by the unit returns to normal range, and once it triggers, the atmospheric pressure monitoring function is deactivated.
The second condition applies only to the 1250AJP model and relates to the main boom angle sensors. The controller stores a serial number for main angle sensor 1 and main angle sensor 2 during calibration. If the system later detects that the sensor connected does not match the serial number it was calibrated against, it logs 'New main angle 1 sensor detected' or 'New main angle 2 sensor detected'. This typically means a sensor was physically replaced or swapped without the machine being recalibrated.
Because boom angle sensors feed the lift's position and load management logic, a mismatch here means the controller cannot fully trust the angle data until recalibration is performed, even though the fault code itself is just a detection notice, not a sensor failure code.
Common causes of 87
- Atmospheric pressure sensed by the control unit hardware falls outside its permissible range, which deactivates the pressure monitoring function until it clears.
- On 1250AJP machines, main angle sensor 1 was physically replaced or swapped, and its serial number does not match the one stored from the last calibration.
- On 1250AJP machines, main angle sensor 2 was physically replaced or swapped, and its serial number does not match the one stored from the last calibration.
How to troubleshoot JLG Articulating Boom Lift 87: first checks
- Cycle the ignition off and on to see if the atmospheric pressure fault message clears once conditions are back in normal range.
- If the fault returns after cycling power, check again and if it remains faulty, contact JLG or OEM service rather than continuing to operate.
- If the message references a new main angle 1 or main angle 2 sensor, confirm whether that sensor was recently replaced or serviced.
- Inspect the wiring and connectors at the main angle sensor for corrosion, looseness, or damage that could cause the controller to misread sensor identity.
- Verify the machine is a 1250AJP if a new-sensor message is displayed, since this variant-specific detection does not apply to other models.
How the code clears
For the atmospheric pressure version, the fault message is designed to disappear on its own once pressure returns to a normal range, and switching the ignition off and then on again is listed as the first step. If the fault persists after that, the guidance is to check again and, if it is still faulty, contact JLG or OEM service. For the new main angle sensor detection on the 1250AJP, no separate clearing step is listed beyond confirming the sensor change and having the machine recalibrated so the controller stores the current sensor's serial number.
Frequently asked questions
What does JLG fault code 87 mean?
It depends on the exact message. It can mean the control unit detected an atmospheric pressure reading outside its permissible range, or on 1250AJP models it can mean the controller detected a main angle 1 or main angle 2 sensor with a different serial number than what it was calibrated with.
Can I keep operating the lift with code 87 active?
The atmospheric pressure version is described as a fault message that clears when pressure returns to normal range, so brief occurrences may resolve themselves. However, if a new main angle sensor is detected, boom angle data may not be fully reliable until the machine is recalibrated, so it's safer to have it checked before continuing normal lifting operations.
Why does my JLG boom lift say a new main angle sensor was detected?
This message appears on 1250AJP models when the serial number of the currently connected main angle sensor 1 or sensor 2 does not match the sensor serial number stored during the last calibration, usually because the sensor was replaced.
How do I clear the atmospheric pressure fault on code 87?
Switch the ignition off and back on first. If the fault message returns, check it again, and if it is still present, contact JLG or OEM service for further diagnosis.
Does code 87 only apply to one JLG model?
The new main angle sensor detection portion of code 87 is specific to the 1250AJP. The atmospheric pressure portion is tied to the control unit hardware generally and is not limited to a single model in the available information.
Will replacing a main angle sensor always trigger code 87?
On the 1250AJP, installing a sensor with a different serial number than what was used during the prior calibration will trigger the new sensor detection message, so recalibration after sensor replacement is expected.