OBD-II DTC · SAE J2012
P2339
Cylinder #4 Above Knock Threshold
What P2339 means
P2339 is a standard SAE J2012 powertrain diagnostic trouble code with the defined meaning: Cylinder #4 Above Knock Threshold. This is the OEM-agnostic definition; specific manufacturer interpretation may add detail (subsystem, bank, sensor location) but the core meaning is consistent across all OBD-II compliant vehicles since 1996.
Common symptoms when P2339 is active
Pulled ignition timing, power loss under load, knock counter increment, knock sensor circuit MIL.
Can this code be suppressed via ECU tuning?
Whether this code is safe to suppress depends on the underlying cause. Diagnose first, suppress only after confirming the mechanical issue is benign or rectified.
How to remove P2339 with Softechpro V5
Recommended service: Not recommended (suppression masks engine damage risk). Step-by-step workflow:
- Knock detection is engine-protective. Suppressing it lets pre-ignition destroy pistons.
- If the knock is false (knock sensor wiring fault): fix the wiring, not the code.
- If you must suppress for a track-only build, Softechpro V5's DTC OFF can mask the specific code — but use at your own risk.
Softechpro V5 supports 1,400+ ECU firmwares across Bosch (EDC15, EDC16, EDC17, MD1, MG1, ME7, MED17), Siemens / Continental (SID, SIMOS, EMS), Delphi (DCM, DDC), and Magneti Marelli platforms.