Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Diagnostic Information and Procedures: Intermittents
DEFINITION:Β
The problem may or may not illuminate the Malfunction Indicator Lamp (MIL) or store a DTC.Β
| Step | Action | Value (s) | Yes | No |
|---|---|---|---|---|
| 1 | Were the Important Preliminary Checks performed? | - | Go to Step 2. | Go to Symptom DiagnosisΒ . |
| 2 |
Are any problems present? |
- | Go to Step 3. | Go to Step 4. |
| 3 | Repair the electrical connections as needed. Is the repair complete? |
- | System OK | - |
| 4 | Road test the vehicle with a voltmeter connected to a suspected circuit or a scan tool connected to the Data Link Connector (DLC). Did the voltmeter or the scan tool indicate an abnormal voltage or scan reading? |
- | Go to Step 5. | Go to Step 6. |
| 5 | Replace the sensor in the affected circuit, if a DTC was stored for this circuit (except for the DTCs P0171 and P0172). Is the repair complete? |
- | System OK | - |
| 6 | Does an intermittent Malfunction Indicator Lamp (MIL) or DTC occur? | - | Go to Step 7. | Go to Step 8. |
| 7 |
Is the repair complete? |
- | System OK | - |
| 8 |
Is DTC P0122 stored in memory? |
- | Go to Step 10. | Go to Step 9. |
| 9 | Replace the ECM. Is the repair complete? |
- | System OK | - |
| 10 | Does the vehicle stall while driving? | - | Go to Step 11. | Go to Step 12. |
| 11 | Monitor the oxygen sensor and the injector base pulse width with the scan tool. Does the scan tool display a steady low voltage (about 0 mV) for the oxygen sensor with the control module commanding an injector base pulse width of the value specified? |
8 ms | Go to Step 9. | Go to Step 12. |
| 12 |
Is the repair complete? |
- | System OK | - |
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.
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