2010 Cadillac Truck SRX FWD V6-3.0L Page 1243
System/Testing and Inspection/Symptoms - Engine Exhaust).
* Malfunctioning fuel injectors-Refer to Fuel Injector Solenoid Coil Test (LAU) (See: Powertrain Management/Fuel Delivery and Air
Induction/Fuel Injector/Testing and Inspection)Fuel Injector Solenoid Coil Test (LF1, LFW) (See: Powertrain Management/Fuel
Delivery and Air Induction/Fuel Injector/Testing and Inspection) ,
* The air intake duct for being collapsed or restricted
* The air filter for being dirty or restricted
* Objects blocking the throttle body
* The evaporative emissions control system for improper operation
* Excessive fuel in the crankcase-Change the oil as necessary.
5. If all conditions test normal, test the engine for a mechanical condition. Refer to Symptoms - Engine Mechanical (See: Engine, Cooling and
Exhaust/Engine/Testing and Inspection/Symptom Related Diagnostic Procedures/Symptoms - Engine Mechanical).
6. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the
conditions that you observed from the Freeze Frame/Failure Records data.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
P0174
DTC P0171, P0172, P0174, or P0175 (LF1)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC P0171
- Fuel Trim System Lean Bank 1
DTC P0172
- Fuel Trim System Rich Bank 1
DTC P0174
- Fuel Trim System Lean Bank 2
DTC P0175
- Fuel Trim System Rich Bank 2
Circuit/System Description
The engine control module (ECM) controls a Closed Loop air/fuel metering system in order to provide the best possible combination of
driveability, fuel economy, and emission control. The ECM monitors the heated oxygen sensor (HO2S) signal voltage, and adjusts the fuel delivery
based on the signal voltage while in Closed Loop. A change made to the fuel delivery changes the long and short term fuel trim values. The short
term fuel trim values change rapidly in response to the HO2S signal voltages. These changes fine tune the engine fueling. The long term fuel trim
values change in response to trends in the short term fuel trim The long term fuel trim makes coarse adjustments to fueling in order to re-center and
restore control to short term fuel trim. The ideal fuel trim values are around 0 %. A positive fuel trim value indicates that the ECM is adding fuel in
order to compensate for a lean condition. A negative fuel trim value indicates that the ECM is reducing the amount of fuel in order to compensate
for a rich condition.
Conditions for Running the DTC
* DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0201-P0206, P0300-P0306, P0442, P0443, P0446, P0449, P0451-P0455, P0496,
P0506, P0507, P2227-P2230, P2269 are not set.
* The engine is in Closed Loop status.
* The engine coolant temperature (ECT) is between -38 and +150掳C (-36 and +302掳F).
* The intake air temperature (IAT) is between -38 and +150掳C (-36 and +302掳F).
* The manifold absolute pressure (MAP) is between 5-255 kPa (1.45-37 psi).
* The vehicle speed is less than 134 km/h (83 mph).
* The engine speed is between 400-6,600 RPM.
* The mass air flow (MAF) is between 0.5-510 g/s.
* The barometric pressure (BARO) is greater than 70 kPa (10.2 psi).
* The fuel level is greater than 10 %.
