Diagnostic Aids

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

Fuel contamination, such as water and alcohol will effect the fuel trim.
The system will go rich if the injectors are supplying too much fuel.
Use a scan tool in order to review the Failure Records. If an intermittent condition is suspected, refer to Testing for Intermittent Conditions and Poor Connections .

DTC P0172

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Are any DTCs other than P0172 also set?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	Go to Step 3
3	Install a scan tool. Review the Freeze Frame/Failure Records and record the displayed data for this DTC. Select Fuel and Emission data list. Start the engine. Observe the Long Term FT parameter with a scan tool. Is the Long Term FT less than the specified value?	-36%	Go to Step 4	Go to Diagnostic Aids
4	Start the engine. Allow the engine to reach operating temperature. Put the transmission in Park or Neutral position. Turn OFF all of the accessories. Allow the engine to idle. Observe the manifold absolute pressure (MAP) sensor parameter with a scan tool. Is the MAP sensor parameter within the specified range?	19-42 kPa	Go to Step 5	Go to DTC P0106
5	Operate the engine at idle. Observe the heated oxygen sensor (HO2S) parameters with a scan tool. Does the scan tool indicate that the values are within the specified range and fluctuating?	200-800 mV	Go to Step 6	Go to Step 7
6	Turn OFF the engine. Visually and physically inspect the following items: The vacuum hoses for splits, kinks, and proper connections-Refer to Emission Hose Routing Diagram . The air intake duct for being collapsed or restricted The air filter for being dirty or restricted For objects blocking the throttle body Did you find and correct the condition?	-	Go to Step 9	Go to Step 8
7	Turn OFF the engine. Inspect for the following conditions: The HO2S for proper installation. Ensure that the electrical connectors and wires are secured and not contacting the exhaust system. The HO2S signal circuit for a short to voltage-Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	-	Go to Step 9	Go to Fuel System Diagnosis
8	Inspect for the following: Excessive fuel in the crankcase The evaporative emissions control system for proper operation The fuel system for proper operation-Refer to Fuel System Diagnosis . Ensure that all injectors are functioning properly. Refer to Fuel Injector Coil Test . Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (With Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool) . Did you find and correct the condition?	-	Go to Step 9	Go to Symptoms - Engine Mechanical
9	IMPORTANT: After repairs, use the scan tool Fuel Trim Reset function in order to reset the Long Term Fuel Trim. Turn ON the ignition, with the engine OFF. IMPORTANT: DO NOT clear codes with the engine running. The codes may reset in the same ignition cycle. 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 10
10	To verify that the performance of the catalytic converter has not been affected by condition that set this DTC, perform the Repair Verification for DTC P0420. Refer to DTC P0420 . Did you complete the procedure?	-	Go to Step 11	Go to DTC P0420
11	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	System OK