Your codes:
P0299 – Turbo Underboost Condition
- Check other service codes first
- Blocked or leaking air intake system
- Damaged turbo charger
- Faulty Boost Pressure Sensor
P0250 - Turbocharger Wastegate Solenoid 2 High Voltage
CRD's have no wastegate, maybe turbo boost control solenoid problem
P0102 - Mass Air Flow Sensor Circuit Low Frequency
- Faulty mass air flow sensor
- Intake air leaks
- Dirty mass air flow sensor
- Dirty mass air filter
- Mass air flow sensor harness is open or shorted
- Mass air flow sensor circuit poor electrical connection
P0504 – Brake Switch Circuit “A” / “B” Correlation
- Faulty stop lamp switch
- Blown stop lamp bulb
- Brake switch harness open or shorted
- Brake switch circuit poor electrical connection

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Supporting Vendor and Moderator of LOST05 Jeep Liberty CRD Limited 
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
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Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount98 Dodge Cummins 24 Valve