I assume you have a 4.3 GM engine. list of codes are attached. You can look each one online for complete definition. Good Luck
GM 4.3L Diagnostic Trouble Codes DTC 111 - IAT High Voltage Bosch® TMAP
DTC 111 - IAT High Voltage Motorola® TMAP
DTC 112 - IAT Low Voltage Bosch® TMap
DTC 112 - IAT Low Voltage Motorola® TMAP
DTC 113 - IAT Higher Than Expected 1 Bosch® TMAP
DTC 113 - IAT Higher Than Expected 1 Motorola® TMAP
DTC 114 - IAT Higher Than Expected 2 Bosch® TMAP
DTC 114 - IAT Higher Than Expected 2 Motorola® TMAP
DTC 115 - Oil Pressure Low
DTC 121 - ECT Voltage High
DTC 122 - ECT Voltage Low
DTC 123 - ECT Higher Than Expected 1
DTC 124 - ECT Higher Than Expected 2
DTC 131 - MAP High Pressure Bosch® TMAP
DTC 131 - MAP High Pressure Motorola® TMAP
DTCC 132 - MAP Low Voltage Bosch® TMAP
DTC 132 - MAP Low Voltage Motorola® TMAP
DTC 134 - BP High Pressure Bosch® TMAP
DTC 134 - BP High Pressure Motorola® TMAP
DTC 135 - BP Low Pressure Bosch® TMAP
DTC 135 - BP Low Pressure Motorola® TMAP
DTC 142 - Crank Sync Noise
DTC 143 - Never Crank Synced At Start
DTC 144 - Camshaft Sensor Loss
DTC 145 - Camshaft Sensor Noise
DTC 211 - Closed Loop Multiplier High (LPG)
DTC 212 - HO2S Open/Inactive
DTC 221 - Closed Loop Multiplier High (Gasoline)
DTC 222 - Closed Loop Multiplier Low (Gasoline)
DTC 224 - Closed Loop Multiplier Low (LPG)
DTC 241 - Adaptive Lean Fault (High Limit-Gasoline)
DTC 242 - Adaptive Rich Fault (Low Limit-Gasoline)
DTC 243 - Adaptive Learn High (LPG)
DTC 244 - Adaptive Learn Low (LPG)
DTC 261 - System Voltage High
DTC 262 - System Voltage Low
DTC 511 - COP Failure
DTC 512 - Invalid Interrupt
DTC 513 - A/D Loss
DTC 514 - RTI 1 Loss
DTC 515 - Flash Checksum Invalid
DTC 516 - Ram Failure
DTC 531 - External 5V Ref Lower Than Expected
DTC 532 - External 5V Ref Higher Than Expected
DTC 555 - RTI 2 Loss
DTC 556 - RTI 3 Loss
DTC 611 - FPP High Voltage
DTC 612 - FPP Low Voltage
DTC 631 - TPS1 Signal Voltage High
DTC 632 - TPS1 Signal Voltage Low
DTC 638 - Throttle Unable To Close
DTC 651 - Maximum Govern Speed Override
DTC 652 - Fuel Rev Limit
DTC 653 - Spark Rev Limit