JLG boom lifts (450AJ, 600AJ, 800AJ, 460SJ, 660SJ, 860SJ, 1250AJP, M450AJ, M600JP)
JLG error code 4379 — SCR CLEANING REQUIRED - CRYSTALLIZATION DETECTED
Message on the display: SCR CLEANING REQUIRED - CRYSTALLIZATION DETECTED
Code 4379 occurs in machines: JLG 1250AJP.
warning / function limited
If ignored the ECM will derate the engine and machine performance will be derated based on severity. ECM will clear fault once successful Regeneration (Standstill Cleaning) has been preformed. The Engine Control Module is reporting that SCR Crystallization has been detected.
Description from the JLG service manual, in the original wording.
Possible causes
The manual does not list the causes for this code: the service technician establishes them during diagnosis of the machine.
Checks from the manual
- Run Regeneration (Standstill Cleaning) via Regeneration (Standstill Cleaning) Switch on the ground panel or JLG Analyzer
What service does
A qualified service technician reads the code with the manufacturer's diagnostic tools, finds the cause, clears the code and carries out a function test.
Source: JLG Service and Maintenance Manuals: 600AJ (3121201), 800AJ (3120858), 460SJ, 860SJ, 1250AJP (3122581800), M450AJ (3121829), M600JP (3121711), Diagnostic Trouble Codes tables.
The descriptions are quoted from the manufacturer's service documentation and are for guidance only. Clearing codes, calibrations and repairs are carried out by a qualified service technician according to the manual for the specific serial number. A machine with an active blocking code must not be used until the cause has been removed.
Does code 4379 not go away?
RK Rental services JLG lifts at our workshop or on site at the customer's premises (construction site, factory, warehouse). We read the code, remove the cause and select the parts by serial number.