Liebherr Fault Code
Free · no signupP20EE-00
Derate Looming. The machine "sees" the exhaust is still dirty after the catalyst.
Variant 1
System
SCR Catalyst
Symptom
Derate Looming. The machine "sees" the exhaust is still dirty after the catalyst.
Diagnosis & fix steps
SCR NOx Catalyst Efficiency Below Threshold.
LOGIC: The difference between the Inlet NOx and Outlet NOx sensors is too small.
ACTION: Perform a DEF Quantity Test (Bucket Test) to ensure the pump is actually spraying.
Red Seal field insights
Pro-Tip: In the Middle East or high-dust regions, the DEF Filter inside the pump gets partially clogged. It sprays enough to not throw a pressure code, but not enough to clean the NOx, triggering P20EE. Red Seal Fix: Always change the pump filter first.
Variant 2
System
Aftertreatment (SCR)
Symptom
Efficiency Alert. "SCR Catalyst Efficiency Below Threshold."
Diagnosis & fix steps
Nitrogen Oxide (NOx) Conversion Too Low.
LOGIC: The downstream NOx sensor sees too much NOx compared to the upstream sensor after DEF injection.
Red Seal field insights
Pro-Tip: This is often a "Crystal" code. Remove the DEF injector and check for a "white mountain" of dried urea at the inlet. If it's clogged, the DEF can't mist properly.
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