Diagnostic Aids

WARNING: This page is about a different variant/trim than selected.

Fuel contamination, such as water or alcohol will effect FT.
A malfunctioning MAF sensor can cause a rich condition and set this DTC. Refer to DTC P0101 .
An evaporative emission (EVAP) canister that is saturated will cause a rich condition. If the conditions were not corrected, a worn cam shaft, worn intake valves, worn exhaust valves, or other engine mechanical failure may be the problem.
Review the Failure Records with a scan tool. If an intermittent condition is suspected, refer to Intermittent Conditions .

DTC P0172 or P0175

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	IMPORTANT: If any DTCs other than P0172 are set, refer to those DTCs before continuing. Install scan tool. Start and idle the engine at the normal operating temperature in Closed Loop. Record the short term and long term fuel trim (FT) data. Turn OFF the engine. Turn ON the ignition, with the engine OFF. Review the Freeze Frame/Failure Records, and record the displayed data for this DTC. Does the scan tool indicate that the combined value of the short term and the long term fuel trim is less than the specified value?	-25%	Go to Step 3	Go to Diagnostic Aids
3	Operate the engine at idle. Observe heated oxygen sensor (HO2S) bank 1 sensor 1 and bank 2 sensor 1 parameters with a scan tool. Does the scan tool indicate that the lambda values are within the specified range?	0.96-1.04	Go to Step 4	Go to Step 5
4	Turn OFF the engine. Visually and physically inspect the following items: The evaporative emission (EVAP) lines and components for damage or blockage The inlet screen of the mass air flow (MAF) sensor for blockage The vacuum hoses for splits, kinks, and proper connections-Refer to Evaporative Emissions Hose Routing Diagram . The air intake duct for being collapsed or restricted The air filter for being dirty or restricted Inspect for objects blocking the throttle body. Did you find and correct the condition?	-	Go to Step 7	Go to Step 6
5	Turn OFF the engine Inspect the HO2S for proper installation. Inspect to ensure that the electrical connectors and the wires are secure and not contacting the exhaust system. Test the HO2S reference voltage current circuit for a short to the following circuits: The input pump current circuit The output pump current circuit Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 7	Go to Step 6
6	Inspect for the following: Excessive fuel in the crankcase Proper operation of the fuel pressure regulator-Refer to Fuel System Diagnosis . All injectors are functioning properly-Refer to Fuel Injector Solenoid Coil Test . Did you find and correct the condition?	-	Go to Step 7	Go to Fuel System Diagnosis
7	IMPORTANT: After repairs, reset the long term fuel with the scan tool Fuel Trim Reset function. Turn ON the ignition, with the engine OFF. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 8
8	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK