Avalanche, Sierra, Silverado, C&K Series, 1999-2005

6.0L V8 VIN U Std 2

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Trouble Code: P0178



Fuel Composition Sensor Low Frequency

Possible Causes:



FCS signal circuit is open or shorted to ground
 
FCS power circuit is open (check power from the ECMI fuse)
 
FCS ground circuit is open between the sensor and the PCM
 
FCS is damaged or has failed
 
PCM is damaged
 

Trouble Code: P0179



Fuel Composition Sensor High Frequency

Possible Causes:



FCS signal circuit is shorted to system power
 
FCS is damaged or has failed
 
PCM is damaged
 

Trouble Code: P0182



Fuel Tank Temperature Sensor Circuit Low Input

Possible Causes:



FTT sensor signal circuit is shorted to chassis or sensor ground
 
FTT sensor is damaged, skewed or it has failed
 
PCM has failed
 

Trouble Code: P0183



Fuel Tank Temperature Sensor Circuit High Input

Possible Causes:



FTT sensor signal circuit or ground circuit is open
 
FTT sensor signal circuit is shorted to VREF
 
FTT sensor is damaged, skewed or it has failed
 
PCM has failed
 

Trouble Code: P0187



Fuel Rail Temperature Sensor Circuit Low Input

Possible Causes:



FRT sensor signal circuit shorted to chassis or sensor ground
 
FRT sensor is damaged, skewed or it has failed
 
PCM has failed
 

Trouble Code: P0188



Fuel Rail Temperature Sensor Circuit High Input

Possible Causes:



FRT sensor signal circuit or ground circuit is open
 
FRT sensor signal circuit is shorted to VREF
 
FRT sensor is damaged, skewed or it has failed
 
PCM has failed
 

Trouble Code: P0191



Fuel Rail Pressure Sensor Circuit Low Input

Possible Causes:



FRP Sensor 5v VREF circuit has a high resistance condition
 
FRP sensor signal circuit has a high resistance condition
 
FRP sensor is damaged or it has failed
 
PCM has failed
 

Trouble Code: P0192



Fuel Rail Pressure Sensor Circuit Low Input

Possible Causes:



FRP sensor 5-volt power circuit is open or shorted to ground
 
FRP Sensor signal circuit is shorted to ground
 
FRP Sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P0193



Fuel Rail Pressure Sensor Circuit High Input

Possible Causes:



FRP sensor signal circuit is open between sensor and the PCM
 
FRP Sensor ground circuit is open between sensor and PCM
 
FRP sensor signal circuit is shorted to VREF or system power
 
FRP Sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P0201



Fuel Injector 1 Control Circuit Malfunction

Possible Causes:



Fuel injector 1 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 1 is damaged or it has failed, or the connector is damaged
 
FICM (module) has failed
 

Trouble Code: P0202



Fuel Injector 2 Control Circuit Malfunction

Possible Causes:



Fuel injector 2 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 2 is damaged or it has failed, or the connector is damaged
 
FICM (module) has failed
 

Trouble Code: P0203



Fuel Injector 3 Control Circuit Malfunction

Possible Causes:



Fuel injector 3 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 3 is damaged or it has failed, or the connector is damaged
 
FICM (module) has failed
 

Trouble Code: P0204



Fuel Injector 4 Control Circuit Malfunction

Possible Causes:



Fuel injector 4 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 4 is damaged or it has failed, or the connector is damaged
 
FICM (module) has failed
 

Trouble Code: P0205



Fuel Injector 5 Control Circuit Malfunction

Possible Causes:



Fuel injector 5 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 5 is damaged or it has failed, or the connector is damaged
 
FICM (module) has failed
 

Trouble Code: P0206



Fuel Injector 6 Control Circuit Malfunction

Possible Causes:



Fuel injector 6 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 6 is damaged or it has failed, or the connector is damaged
 
FICM (module) has failed
 

Trouble Code: P0207



Fuel Injector 7 Control Circuit Malfunction

Possible Causes:



Fuel injector 7 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 7 is damaged or it has failed, or the connector is damaged
 
FICM (module) has failed
 

Trouble Code: P0208



Fuel Injector 8 Control Circuit Malfunction

Possible Causes:



Fuel injector 8 connector is damaged, loose or shorted
 
Fuel injector 8 control circuit is open, shorted to ground or shorted to power
 
Fuel injector 8 is damaged or it has failed
 
FICM (module) has failed
 

Trouble Code: P0230



Fuel Pump Relay Control Circuit Malfunction

Possible Causes:



Fuel pump relay control circuit is open or shorted to ground
 
Fuel pump relay power circuit is open (PCM Fuse B fuse block)
 
Fuel pump relay is damaged or it has failed
 
PCM is damaged
 

Trouble Code: P0401



Insufficient EGR Flow Detected

Possible Causes:



Base engine problem (e.g., a severely restricted exhaust)
 
EGR vacuum hoses damaged, loose or routed incorrectly
 
EGR passages or intake passages clogged or restricted
 
EGR solenoid valve is clogged (carbon), damaged or has failed
 

Trouble Code: P0404



EGR Open Position Signal Range/Performance

Possible Causes:



EGR sensor signal circuit is open, shorted to ground or power
 
EGR sensor ground or VREF circuit is open
 
EGR valve seat or pintle contains debris or carbon (inspect and clean)
 
EGR valve is contaminated, clogged, damaged or has failed
 
PCM has failed
 

Trouble Code: P0405



EGR Position Sensor Circuit Low Input

Possible Causes:



EGR position sensor signal circuit is open
 
EGR position sensor signal circuit is shorted to ground
 
EGR position sensor VREF circuit is open or shorted to ground
 
EGR position sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P0420



Catalyst System Low Efficiency (Bank 1)

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Base engine problems (i.e., high engine oil or coolant usage)
 
Catalytic converter is damaged, contaminated or has failed
 
Continuous engine misfire conditions, or weak or low coil output
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 
Rear HO2S is loose in the mounting hole (check it for a leak)
 
TSB 81-65-37 contains a repair procedure for this code
 

Trouble Code: P0430



Catalyst System Low Efficiency (Bank 2)

Possible Causes:



Air leaks at the exhaust manifold or in the exhaust pipes
 
Base engine problems (i.e., high engine oil or coolant usage)
 
Catalytic converter is damaged, contaminated or has failed
 
Continuous engine misfire conditions, or weak or low coil output
 
Front HO2S or rear HO2S is contaminated with fuel or moisture
 
Rear HO2S is loose in the mounting hole (check it for a leak)
 
TSB 81-65-37 contains a repair procedure for this code
 

Trouble Code: P0442



EVAP System Small Leak (0.040") Detected

Possible Causes:



Charcoal canister is loaded with fuel or moisture
 
Fuel filler cap is loose, cross-threaded, damaged or wrong part
 
Fuel tank, fuel filler neck or fuel sending unit 'O' ring is leaking
 
Fuel tank pressure sensor is damaged, disconnected or it failed
 
Fuel tank or purge valve vapor lines clogged or disconnected
 
Purge solenoid or Vent solenoid has a small leaking (sticking)
 
PCM has failed
 

Trouble Code: P0443



EVAP Purge Solenoid Control Circuit Malfunction

Possible Causes:



Purge solenoid control circuit is open or shorted to ground
 
Purge solenoid control circuit is shorted to system power (B+)
 
Purge solenoid power circuit is open (test the ENG1 fuse)
 
Purge solenoid is damaged or has failed
 
PCM has failed
 

Trouble Code: P0446



EVAP Vent System Performance

Possible Causes:



EVAP vent fresh air hose is clogged, kinked or restricted
 
EVAP Vent solenoid is contaminated, damaged or has failed
 
EVAP Canister plugged or severely restricted
 
Fuel Cap or EVAP Service Port leaking
 
Fuel vapor lines or purge lines damaged or leaking
 
FTP sensor is out-of-calibration, damaged or "skewed"
 
PCM has failed
 
TSB 02-06-04-037 contains a repair procedure for this code
 

Trouble Code: P0449



EVAP Vent Solenoid Control Circuit Malfunction

Possible Causes:



Vent solenoid control circuit is open or shorted to ground
 
Vent solenoid control circuit is shorted to system power (B+)
 
Vent solenoid power circuit is open (test the ENG1 fuse)
 
Vent solenoid is damaged or has failed
 
PCM has failed
 

Trouble Code: P0452



Fuel Tank Pressure Sensor Circuit Low Input

Possible Causes:



FTP sensor connector is damaged or shorted
 
FTP sensor signal circuit is open or shorted to ground
 
FTP sensor VREF circuit is open or shorted to ground
 
FTP sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P0453



Fuel Tank Pressure Sensor Circuit High Input

Possible Causes:



FTP sensor connector is damaged, loose or open
 
FTP sensor signal circuit is shorted to VREF (5v)
 
FTP sensor ground circuit is open between sensor and PCM
 
FTP sensor is damaged or has failed
 
PCM has failed
 

Trouble Code: P0455



EVAP System Large Leak (0.080") Detected

Possible Causes:



Fuel filler cap is very loose, missing or the wrong part
 
Fuel tank, fuel filler neck or fuel sending unit 'O' ring is leaking
 
Fuel tank pressure sensor is damaged, disconnected or it failed
 
Fuel tank vapor line(s) is clogged, damaged or disconnected
 
Purge valve vapor line is clogged, damaged, or disconnected
 
Purge solenoid is not opening (it may be damaged or sticking)
 
Vent solenoid is not closing (it may be damaged or sticking)
 
PCM has failed
 

Trouble Code: P0461



Fuel Level Sensor Range/Performance

Possible Causes:



Fuel level sensor signal circuit is open or shorted to ground between the fuel level sensor and the PCM connector
 
Fuel level sensor ground circuit is open or has high resistance
 
Fuel level sender is damaged, binding or not aligned properly
 
Instrument cluster or the PCM has failed
 

Trouble Code: P0462



Fuel Level Sensor Low Input

Possible Causes:



Fuel level sensor signal circuit is shorted to ground between the fuel level sensor and the PCM connector
 
Fuel level sender is damaged, binding or not aligned properly
 
PCM has failed
 

Trouble Code: P0463



Fuel Level Sensor High Input

Possible Causes:



Fuel level sensor signal circuit is shorted to system power
 
Fuel level sensor ground circuit is open
 
Fuel level sender is damaged, binding or not aligned properly
 
PCM has failed
 

Trouble Code: P0496



EVAP Canister Purge System High Purge Flow

Possible Causes:



EVAP charcoal canister is damaged or restricted
 
EVAP purge pipe is damaged or restricted
 
FTP sensor is damaged or it has failed
 
Purge solenoid is damaged (it may be sticking)
 
Purge solenoid valve has failed
 

Trouble Code: P0500



Vehicle Speed Sensor Circuit Malfunction

Possible Causes:



Output shaft rotor is chipped or damaged
 
Output shaft rotor is not aligned properly with the VSS unit
 
VSS tip contains debris or metal shavings (an intermittent fault)
 
VSS positive (+) signal circuit is open or shorted to ground
 
VSS negative (-) signal circuit is open or shorted to ground
 
VSS is damaged or has failed
 

Trouble Code: P0506



Idle Speed Too Low

Possible Causes:



Air inlet duct is collapsed, loose or air filter element is clogged
 
Base engine problem (i.e., compression or misfire condition)
 
IAC solenoid control circuit has a high resistance condition
 
IAC valve is damaged or has failed
 
Idle air inlet passage or throttle bore is dirty or full of deposits
 
MAF sensor is dirty, out-of-calibration or it is "skewed"
 
PCM has failed
 

Trouble Code: P0507



Idle Speed Too High

Possible Causes:



Engine vacuum leaks, PCM valve is leaking or the wrong valve
 
Idle air inlet passage or throttle bore is dirty or full of deposits
 
IAC valve is damaged or has failed
 
MAF sensor is dirty, "skewed" or installed improperly
 
Throttle plate, throttle shaft or linkage is damaged or sticking
 
TP sensor is out-of-range or "skewed" high
 
PCM has failed
 

Trouble Code: P0562



System Voltage Too Low

Possible Causes:



Check for high resistance at battery connections or the MINI fuse power circuit
 
Check the drive belt for excessive wear and the proper tension
 
Check the condition of the battery and the Generator output
 
Vehicle may have been used to jump-start another vehicle
 

Trouble Code: P0563



System Voltage Too High

Possible Causes:



Check the condition of the battery (it may be worn out)
 
Test the operation of the Generator (it may have failed)
 
Vehicle may have been used to jump-start another vehicle
 

Trouble Code: P0601



Control Module ROM Malfunction

Possible Causes:



The PCM must be replaced to correct this problem. A new PCM must be programmed with the correct software/calibration.
 
TSB 67-65-23 contains a repair procedure for this code
 

 
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