Fault Phenomenon: Caterpillar 336 excavator engine fault light illuminates, power is limited, fuel consumption increases.

Troubleshooting Process:
– Read fault codes: EGR flow anomaly.
– Remove valve: valve stem severely carbonized and stuck.
– Checked lines: EGR cooler clogged.
– Checked fuel: high sulfur content.

Root Cause: The Exhaust Gas Recirculation (EGR) valve is severely stuck due to carbon buildup, affecting intake air volume and combustion efficiency.

Required Parts: EGR valve assembly and clean lines.