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

6.6L V8 VIN 1 Std 3

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Trouble Code: P1020



Camshaft Phasing System Malfunction

Possible Causes:



AF fuel mode relay circuit (odd bank, even bank) is open
 
AF enable circuit is open or shorted to ground
 
FICM is damaged or it has failed
 

Trouble Code: P1021



CNG Fuel Injector 1 Circuit Malfunction

Possible Causes:



CNG fuel injector 1 control circuit is open or shorted to ground
 
CNG fuel injector 1 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1022



CNG Fuel Injector 2 Circuit Malfunction

Possible Causes:



CNG fuel injector 2 control circuit is open or shorted to ground
 
CNG fuel injector 2 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1023



CNG Fuel Injector 3 Circuit Malfunction

Possible Causes:



CNG fuel injector 3 control circuit is open or shorted to ground
 
CNG fuel injector 3 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1024



CNG Fuel Injector 4 Circuit Malfunction

Possible Causes:



CNG fuel injector 4 control circuit is open or shorted to ground
 
CNG fuel injector 4 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1025



CNG Fuel Injector 5 Circuit Malfunction

Possible Causes:



CNG fuel injector 5 control circuit is open or shorted to ground
 
CNG fuel injector 5 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1026



CNG Fuel Injector 6 Circuit Malfunction

Possible Causes:



CNG fuel injector 6 control circuit is open or shorted to ground
 
CNG fuel injector 6 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1027



CNG Fuel Injector 7 Circuit Malfunction

Possible Causes:



CNG fuel injector 7 control circuit is open or shorted to ground
 
CNG fuel injector 7 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1028



CNG Fuel Injector 8 Circuit Malfunction

Possible Causes:



CNG fuel injector 8 control circuit is open or shorted to ground
 
CNG fuel injector 8 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1093



Fuel Rail Pressure Range/Performance

Possible Causes:



CNG fuel injector 8 connector is damaged, open or shorted
 
CNG fuel injector 8 control circuit is open or shorted to ground
 
CNG fuel injector 8 is damaged or it has failed
 
FICM has failed
 

Trouble Code: P1094



Fuel Rail Pressure Solenoid Circuit Malfunction

Possible Causes:



Check the engine oil for fuel contamination
 
Fuel pressure regulator solenoid circuit is shorted to ground
 
If you have to prime the fuel system, inspect for a restricted fuel supply line or a fuel supply line air leak
 
ECM has failed
 

Trouble Code: P1125



Accelerator Pedal Position Sensor Circuit Malfunction

Possible Causes:



If DTC P0641 is set, repair the cause of this trouble code first.
 
If DTC P0641 is not set, refer to the other APP sensor codes that are set to repair the cause of this trouble code.
 

Trouble Code: P1172



Secondary Fuel Pump Insufficient/No Fuel Flow

Possible Causes:



Fuel transfer relay control circuit is open or shorted to ground
 
Fuel pump relay ground circuit is open
 
Fuel pump relay power circuit is open (check the ECB B fuse)
 
Fuel pump relay or the Fuel transfer pump is damaged or has failed
 
ECM has failed
 

Trouble Code: P1201



Gas Mass Sensor Range/Performance

Possible Causes:



Air filter or air inlet duct is clogged or restricted
 
Air leaks in the exhaust pipes or manifold, or the HO2S location
 
Base engine problem (i.e., engine compression, vacuum leak)
 
CNG system fuel pressure is incorrect
 
PCV system problem (i.e., PCV vacuum hose or valve leaking)
 
EVAP canister purge system malfunction
 
Gasoline contaminated engine oil
 
Fuel pressure regulator damage or leaking
 
PCM has failed
 

Trouble Code: P1207



FICM PWM Signal To PCM Circuit Malfunction

Possible Causes:



FICM sensor PWM signal circuit is open or shorted to ground
 
FICM is damaged or it has failed
 
PCM has failed
 

Trouble Code: P1214



Injection Pump Timing Offset

Possible Causes:



The PCM will only run the test if the TDC offset adjustment time set procedure has been activated. The vehicle will most likely not be brought in with this code in memory.
 
CKP sensor incorrectly installed or mounting tab is broken
 
Fuel injection pump is damaged or has failed (a new pump will need to be "timed" using the correct pump timing procedure)
 

Trouble Code: P1215



High Pressure Or Low Pressure Lockout, MIL, NGO Circuit Malfunction

Possible Causes:



Natural Gas Output Enable, High Pressure Lockout, Low Pressure Lockout or MIL control circuit is open, shorted to ground or shorted to system power
 
Alternative Fuels ECU is damaged or has failed
 

Trouble Code: P1216



Fuel Solenoid Response Time Too Short

Possible Causes:



Intermittent P0251, P0370, and P1216 codes may be caused by air entering the fuel system when fuel levels get below 1/8 of a tank during hard acceleration or turning maneuvers. Codes P0251, P0370, and P1216 may set if the vehicle has run out of fuel. Customer driving habits should be checked to determine if the vehicle has been performing in these manners. If the vehicle has performed in these conditions, bleed the fuel system of all air and then perform a complete vehicle test drive.
 
Injection pump timing circuit is open, shorted to ground or to B+
 
TSB 77-63-06A contains a repair procedure for this code
 

Trouble Code: P1217



Fuel Solenoid Response Time Too Long

Possible Causes:



Fuel solenoid driver power circuit is open (test FUEL SOL fuse)
 
Fuel solenoid high circuit is open or shorted to ground
 
Fuel solenoid low circuit is open
 
Fuel solenoid is damaged or has failed (solenoid may be weak)
 
Fuel solenoid driver has failed
 

Trouble Code: P1218



Injection Pump Calibration Circuit Malfunction

Possible Causes:



Fuel solenoid driver connections have a problem
 
Fuel solenoid is damaged or has failed
 
Fuel injection pump is damaged or has failed (a new pump will need to be "timed" using the correct pump timing procedure)
 

Trouble Code: P1223



Fuel Injector 1 Control Circuit Low Input

Possible Causes:



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

Trouble Code: P1226



Fuel Injector 2 Control Circuit Low Input

Possible Causes:



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

Trouble Code: P1232



Fuel Injector 4 Control Circuit Low Input

Possible Causes:



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

Trouble Code: P1235



Fuel Injector 5 Control Circuit Low Input

Possible Causes:



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

Trouble Code: P1238



Fuel Injector 6 Control Circuit Low Input

Possible Causes:



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

Trouble Code: P1241



Fuel Injector 7 Control Circuit Low Input

Possible Causes:



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

Trouble Code: P1244



Fuel Injector 8 Control Circuit Low Input

Possible Causes:



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

Trouble Code: P1261



Fuel Pump Relay Circuit Malfunction (Injectors 1, 4, 6 or 7)

Possible Causes:



One or more injector control circuits open or shorted to ground
 
One or more injector power circuits open or injector is damaged
 
Injector relay power or ground circuit is open, or relay has failed
 
FICM (module) has failed
 
ECM (module) has failed
 

Trouble Code: P1262



Fuel Pump Relay Circuit Malfunction (Injectors 2, 3, 5 or 8)

Possible Causes:



One or more injector control circuits open or shorted to ground
 
One or more injector power circuits open or injector is damaged
 
Injector relay power or ground circuit is open, or relay has failed
 
FICM (module) has failed
 
ECM (module) has failed
 

Trouble Code: P1270



Fuel Pump Relay Circuit Malfunction (Injectors 2, 3, 5 or 8)

Possible Causes:



ECM is damaged or it has failed. Clear the codes and then retest for this same trouble code. If it resets, the ECM must be replaced and reprogrammed to repair this code.
 

Trouble Code: P1336



CKP Sensor System Variation Not Learned

Possible Causes:



Set the parking brake and block the drive wheels for safety.
 
Verify the hood is closed.
 
Read the trouble codes. If a code is set, refer to that code.
 
Start the engine. Allow engine temperature to reach at least 158ºF (70ºC). Then key off.
 
Select Crankshaft Position Variation Learn procedure on Scan Tool & start the vehicle.
 
Apply the brake pedal firmly and verify the selector is in Park.
 
Increase accelerator pedal position until fuel cutoff is reached at the test rpm (e.g., 5150). Quickly release the accelerator pedal after fuel cutoff is reached. The CKP system variation compensating values are learned when the engine speed (rpm) decreases back to idle speed and the procedure terminates.
 
Read the trouble codes and recheck for DTC P1336.
 
If DTC P1336 runs and passes, the CKP system variation "learn" procedure is complete. If not, look for other codes. If no codes are set, repeat the test procedure.
 

Trouble Code: P1404



EGR Valve Vacuum Sensor Range/Performance

Possible Causes:



Check for leaking or restricted vacuum line connections
 
EGR vacuum sensor is damaged or it has failed
 
EGR vacuum vent solenoid is stuck open
 
EGR valve is damaged or it has failed
 
EGR valve vacuum control solenoid is stuck open
 
EGR vent solenoid is damaged or it has failed
 
Exhaust system may be restricted causing high back pressure
 

Trouble Code: P1432



Fuel Pressure Sensor Circuit Low Input

Possible Causes:



Fuel tank pressure sensor is sticking or it is damaged
 
Fuel tank pressure sensor signal circuit is shorted to ground
 
Fuel tank pressure sensor is damaged or it has failed
 
PCM has failed
 

Trouble Code: P1433



Fuel Pressure Sensor Circuit Low Input

Possible Causes:



Fuel tank pressure sensor is sticking or it is damaged
 
Fuel tank pressure sensor signal circuit is shorted to ground
 
Fuel tank pressure sensor is damaged or it has failed
 
PCM has failed
 

Trouble Code: P1550



Fuel Injector Control Module Power Circuit Malfunction

Possible Causes:



FICM ground circuit has a high resistance condition
 
FICM power circuit has a high resistance condition
 
FICM (module) is damaged or it has failed
 

Trouble Code: P1635



5-Volt Reference Circuit Low Input

Possible Causes:



5v VREF circuit is shorted to sensor ground or chassis ground
 
5v VREF circuit, Boost or CKP sensor circuit is shorted to (B+)
 
5v VREF circuit shorted to the Boost sensor signal circuit
 
EGR solenoid valve (and sensor) is damaged or has failed
 
PCM has failed
 

Trouble Code: P1639



5-Volt Reference Circuit Low Input

Possible Causes:



5v VREF circuit is shorted to sensor ground or chassis ground
 
5v VREF circuit, Boost or CKP sensor circuit is shorted to (B+)
 
5v VREF circuit shorted to the Boost sensor signal circuit
 
EGR solenoid valve (and sensor) is damaged or has failed
 
PCM has failed
 

Trouble Code: P1658



Fuel Injection Control Module Internal Malfunction

Possible Causes:



FICM has failed. There is no external failure that can cause DTC P1658 to set. This code is due to an internal circuit failure (i.e., this code indicates a FICM replacement).
 

Trouble Code: P2123



Accelerator Pedal Position Sensor 1 High Input

Possible Causes:



APP sensor 1 signal circuit is shorted to VREF
 
APP sensor low reference circuit is open or shorted to VREF
 
APP sensor is damaged or it has failed
 
ECM has failed
 

Trouble Code: P2127



Accelerator Pedal Position Sensor 2 Low Input

Possible Causes:



APP sensor connector is damaged or shorted
 
APP sensor 2 signal circuit is open or shorted to ground
 
APP sensor is damaged or it has failed
 
ECM has failed
 

 
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