Test Description
The number below refers to the step number on the diagnostic table.
- 8:
If conditions were not corrected, a worn cam, worn intake or exhaust valves or other engine mechanical failure may be at fault.
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 DTC 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 Trim Data parameter.
- Start the engine.
- Observe the Long Term FT parameter with a scan tool.
Is the Long Term FT parameter less than the specified value? |
-19% |
Go to Step 4 |
Go to Diagnostic Aids |
| 4 |
- Start the engine.
- Allow the engine to reach operating temperature.
- Put the transmission in the 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? |
40-900 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
- 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: 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 |
Observe the Capture Info with a scan tool. Have any other DTCs not been diagnosed? |
- |
Go to Diagnostic Trouble Code (DTC) List - Vehicle |
System OK |