Diagnostic Aids
WARNING: This page is about a different variant/trim than selected.
- Excessive resistance in the fuel injector ignition 1 voltage circuit or the fuel injector control circuit may cause the following symptoms:
- Lean condition
- Misfire
- Rough idle
- The system will go lean if an injector is not suppling enough fuel.
- A lean condition could be present during high fuel demand.
- A malfunctioning MAF sensor can cause this DTC to set. Refer to DTC P0101
.
- Review the Failure Records with a scan. If an intermittent condition is suspected, refer to Intermittent Conditions
.
DTC P0171 or P0174
| 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 P0171 or P0174 are set, refer to those DTCs before continuing.
- Install the 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).
- 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 greater than the specified value? |
25% |
Go to Step 3 |
Go to Diagnostic Aids |
| 3 |
- Operate the engine at idle.
- Observe the 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:
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.
- Verify the electrical connectors and the wires are secure, and not contacting the exhaust system.
- Test the HO2S reference voltage circuit for a short to the following circuits:
Did you find and correct the condition? |
- |
Go to Step 7 |
Go to Fuel System Diagnosis |
| 6 |
- Operate the engine at idle.
- Inspect for any missing, loose, or leaking exhaust components forward of the HO2S.
- Inspect for vacuum leaks at the intake manifold, throttle body, and injector O-rings.
- Inspect the air induction system and the air intake ducts for leaks.
- Inspect the crankcase ventilation system for leaks. Refer to Crankcase Ventilation System Inspection/Diagnosis
in Engine Mechanical.
Did you find and correct the condition? |
- |
Go to Step 7 |
Go to Symptoms - Engine Mechanical
in Engine Mechanical |
| 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 |