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DTC P0172: Fuel Trim System Rich: Troubleshooting

TROUBLESHOOTING CHART

Step Action Value(s) Yes No
1 Perform an On-Board Diagnostic (OBD) System Check.
Is the system check complete?		 - Go to Step 2 Go to On-Board Diagnostic (OBD II) System Check
2
  1. Install the scan tool to the Data Link Connector (DLC).
  2. Turn the ignition ON.

Are any component related Diagnostic Trouble Codes (DTCs) set?		 - Go to applicable DTC table Go to Step 3
3 With the engine running, operate the vehicle until the Loop Status indicates closed.
Is the Long Term Fuel Trim value above the specified value?		 -32% Go to Step 4 Go to Step 5
4
  1. Turn the ignition switch ON, with the engine OFF.
  2. Review the Freeze Frame data and note the parameters.
  3. Operate the vehicle within the Freeze Frame conditions and Conditions for Setting The DTC as noted.

Does the Long Term Fuel Trim value above the specified value while operating under the specified conditions?		 -32% Go to Step 21 Go to Step 5
5 Visually/Physically check the air cleaner filter for excessive dirt or being plugged and repair as needed.
Is the repair complete?		 - Go to Step 21 Go to Step 6
6 Visually/Physically check the air intake system for collapsed or restricted and repair as needed.
Is the repair complete?		 - Go to Step 21 Go to Step 7
7 Inspect the throttle body inlet for damaged or foreign objects which may partially block the airflow and repair as needed.
Is the repair complete?		 - Go to Step 21 Go to Step 8
8
  1. Turn the ignition OFF.
  2. Inspect the throttle bore and throttle plate for choking and foreign objects and repair as needed.

Is the repair complete?		 - Go to Step 21 Go to Step 9
9
  1. Turn the ignition OFF.
  2. Disconnect the Manifold Absolute Pressure (MAP) sensor electrical connector.
  3. Start the engine.
  4. Operate the vehicle in Closed Loop while monitoring the Long Term Fuel Trim value.

Does the Long Term Fuel Trim value increase above the specified value?		 -32% Go to Step 14 Go to Step 10
10
  1. Perform the Fuel System Diagnosis.
  2. If the table isolate a problem, repair as needed.

Is the repair complete?		 - Go to Step 15 Go to Step 11
11
  1. Perform the Evaporative (EVAP) emission control system diagnosis.
  2. If the table isolate a problem, repair as needed.

Is the repair complete?		 - Go to Step 15 Go to Step 12
12
  1. Perform the FUEL INJECTOR BALANCE TEST .
  2. If the table isolate a problem, repair as needed.

Is the repair complete?		 - Go to Step 15 Go to Step 13
13
  1. Remove the Heated Oxygen Sensor (HO2S).
  2. Visually/Physically inspect the HO2S for silicone contamination.
    NOTE: This will be indicated by a powdery white deposit on the portion of the HO2S exposed to the exhaust stream.
  3. If contamination is present on the HO2S, find the source and repair as needed.

Is the repair complete?		 - Go to Step 15 Go to Diagnostic Aids
14
  1. Turn the ignition OFF.
  2. Replace the MAP sensor.

Is the repair complete?		 - Go to Step 15 -
15
  1. Using the scan tool, clear the Diagnostic Trouble Codes (DTCs).
  2. Start the engine and idle at normal operating temperature.
  3. Operate the vehicle within the Conditions for setting this DTC as specified in the supporting text.

Does the scan tool indicate that this diagnostic has run and passed?		 - Go to Step 16 Go to Step 2
16 Check if any additional DTCs are set.
Are any DTCs displayed that have not been diagnosed?		 - Go to applicable DTC table System OK
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