CONDITIONS FOR RUNNING THE DTC
DTCs P0030, P0036, P0068, P0101, P0102, P0103, P0106, P0107, P0108, P0117, P0118, P0120, P0121,
P0128, P0130, P0131, P0132, P0133, P0134, P0135, P0136, P0137, P0138, P0140, P0141, P0201-P0208,
P0220, P0300, P0301-P0304, P0442, P0443, P0446, P0449, P0452, P0453, P0455, P0496, P1106, P1107,
P1114, P1115, P1133, P1516, P2101, P2119, P2120, P2125, P2135, P2138, P2176 are not set.
The engine is in Closed Loop status.
The engine coolant temperature (ECT) is between -40 and +150°C (-40 and +302°F).
The intake air temperature (IAT) is between -20 and +150°C (-4 and +302°F).
The manifold absolute pressure (MAP) is between 10-255 kPa (1.45-37 psi).
The vehicle speed is less than 134 km/h (83 mph).
The engine speed is between 375-7,000 RPM.
The mass air flow (MAF) is between 1-510 g/s.
The barometric pressure (BARO) is more than 70 kPa (10.2 psi).
The fuel level is more than 10 percent.
This diagnostic runs continuously when the above conditions have been met.
CONDITIONS FOR SETTING THE DTC
The average long term FT weighted average value is more or less than a calibrated value.
The above condition is present for approximately 3 minutes after the Conditions for Running the DTC
have been met.
ACTION TAKEN WHEN THE DTC SETS
The control module records the operating conditions at the time the diagnostic fails. The first time the
diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a
failure on the second ignition cycle the control module records the operating conditions at the time of the
failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure
Records. The control module illuminates the malfunction indicator lamp (MIL) when one of the following
occur:
The control module detects the same fuel trim failure during 2 consecutive trips.
The control module detects any fuel trim failure during any subsequent trip if the conditions at the time of
failure meet the following criteria:
The engine load is within 20 percent of the previous test that failed.
The engine speed is within 375 RPM of the previous test that failed.
The engine coolant temperature is in the same range of the previous test that failed.
CIRCUIT/SYSTEM TESTING
P0171 or P0174
Allow the engine to reach operating temperature. With the engine running, observe the affected Long Term FT
parameter with a scan tool. The value should be less than approximately 20 percent with the engine running at
operating temperature.
If the value is not less than 20 percent, inspect for the following:
With the ignition ON and the engine OFF, observe the manifold absolute pressure (MAP) sensor
parameter. The MAP sensor pressure should be within the range specified for your altitude. Refer to
Altitude Versus Barometric Pressure .
Refer to DTC P0106 if the MAP sensor does not indicate the correct barometric pressure.
With the engine idling, observe the mass air flow (MAF) sensor parameter. The MAF sensor parameter
should be within 2-6 g/s at idle.
Refer to DTC P0101 or P1101 or DTC P0102 or P0103 if the MAF sensor parameter is not within
2-6 g/s at idle.
Vacuum hoses for splits, kinks, and improper connections-Refer to Emission Hose Routing Diagram .
Insufficient fuel in the tank
Low fuel pressure-Refer to Fuel Pump Electrical Circuit Diagnosis .
Fuel contamination-Refer to Evaporative Emission System Diagnosis .
Malfunctioning fuel injectors-Refer to Fuel Injector Diagnosis (w/J39021 or Tech 2) or Fuel Injector
Diagnosis (w/CH47976) .
Missing, loose, or leaking exhaust components from the HO2S forward-Refer to Symptoms - Engine
Exhaust .
Vacuum leaks at the intake manifold, the throttle body, and the injector O-rings
The air induction system and the air intake ducts for leaks or for a missing air filter element
A cracked EVAP canister
Evaporative pipes obstructed or leaking-Refer to Fuel Hose/Pipes Routing Diagram .
The crankcase ventilation system for leaks
The HO2S for improper installation and for electrical wires or connectors that may have contacted the
exhaust system
The HO2S signal circuit open, shorted to ground, or shorted to the low reference circuit
Malfunctioning engine components-Refer to Symptoms - Engine Mechanical .
P0172 or P0175
Allow the engine to reach operating temperature. With the engine running, observe the affected Long Term FT
parameter with a scan tool. The value should be more than approximately -20 percent with the engine running at
operating temperature.
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Controls and Fuel - 4.3L - Sierra & Silverado
If the value is not more than -20 percent, inspect for the following:
With the engine idling and the transmission in the Park or Neutral position, observe the manifold absolute
pressure (MAP) sensor parameter. The MAP sensor parameter should be between 19-42 kPa.
Refer to DTC P0106 if the MAP sensor parameter is not between 19-42 kPa.
With the engine idling, observe the mass air flow (MAF) sensor parameter. The MAF sensor parameter
should be within 2-6 g/s at idle.
Refer to DTC P0101 or P1101 or DTC P0102 or P0103 if the MAF sensor parameter is not within
2-6 g/s at idle.
Vacuum hoses for splits, kinks, and improper connections-Refer to Emission Hose Routing Diagram .
The air intake duct for being collapsed or restricted
The air filter for being dirty or restricted
Objects blocking the throttle body
Excessive fuel in the crankcase due to leaking fuel injectors
The evaporative emissions control system for improper operation-Refer to Fuel Hose/Pipes Routing
Diagram .
Excessive fuel pressure-Refer to Fuel Pump Electrical Circuit Diagnosis .
Malfunctioning fuel injectors-Refer to Fuel Injector Diagnosis (w/J39021 or Tech 2) or Fuel Injector
Diagnosis (w/CH47976) .
Fuel contamination-Refer to Evaporative Emission System Diagnosis .
The HO2S for improper installation and for electrical wires or connectors that may have contacted the
exhaust system
The HO2S signal circuit shorted to voltage
