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 Test
- CHECK FOR AN ACTIVE DTC NOTE:
Check for contaminates that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.
- Start the engine.
- Allow the engine to reach normal operating temperature.
- With the scan tool, read DTCs and record on the repair order.NOTE:
It may be necessary to drive the vehicle to meet the conditions to set this DTC, try to repeat the conditions in which the fault originally set by reviewing the Freeze Frame data.
Is the DTC active or pending?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. Refer to INTERMITTENT CONDITION .
- CHECKING FUEL DELIVERY SYSTEM FOR PROPER OPERATION
- Perform the CHECKING THE FUEL DELIVERY SYSTEM test procedure. Refer to CHECKING THE FUEL DELIVERY SYSTEM (HARD START)
.
Were any problems found with the fuel system?
Yes
- Perform the appropriate repair.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 3
- Perform the CHECKING THE FUEL DELIVERY SYSTEM test procedure. Refer to CHECKING THE FUEL DELIVERY SYSTEM (HARD START)
.
- CHECK THE O2 SENSOR FOR PROPER OPERATION
- Perform the CHECKING THE OXYGEN SENSOR OPERATION test procedure. Refer to CHECKING THE OXYGEN SENSOR OPERATION
.
Were any problems found with the O2 Sensors?
Yes
- Perform the appropriate repair.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 4
- Perform the CHECKING THE OXYGEN SENSOR OPERATION test procedure. Refer to CHECKING THE OXYGEN SENSOR OPERATION
.
- CHECK THE MAP SENSOR FOR PROPER OPERATION
- Perform the CHECKING THE MAP SENSOR OPERATION test procedure. Refer to CHECKING THE MAP SENSOR OPERATION
.
Were any problems found with the MAP Sensor?
Yes
- Perform the appropriate repair.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 5
- Perform the CHECKING THE MAP SENSOR OPERATION test procedure. Refer to CHECKING THE MAP SENSOR OPERATION
.
- CHECK THE EVAP PURGE SOLENOID FOR PROPER OPERATION
- Turn the ignition off.
- Disconnect the hoses at the Evap Purge Solenoid.
- Using a hand vacuum pump, apply 5 inches of vacuum to the Evap Purge Solenoid vacuum source port on the engine side.
Did the Evap Purge Solenoid hold vacuum?
Yes
- Go To 6
No
- Verify that there is good pin to terminal contact in the Solenoid and Powertrain Control Module connectors. Replace the Evap Purge Solenoid if no problems were found with the connectors. Refer to SOLENOID, EVAPORATIVE EMISSIONS PURGE, REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST
.NOTE:
Reconnect the vacuum hoses before continuing.
- CHECK THE ENGINE MECHANICAL CONDITION
- Check for any of the following conditions/mechanical problems.
- AIR INDUCTION SYSTEM - must be free from restrictions.
- ENGINE VACUUM - must be at least 13 inches in neutral
- ENGINE VALVE TIMING - must be within specifications
- ENGINE COMPRESSION - must be within specifications
- ENGINE PCV SYSTEM - must flow freely
- FUEL INJECTOR - plugged or restricted injector; control wire not connected to correct injector
Are there any engine mechanical problems?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- Go To 7
- Check for any of the following conditions/mechanical problems.
- CHECK RELATED HARNESS CONNECTIONS
- Disconnect all PCM harness connectors.
- Disconnect all related in-line harness connections (if equipped).
- Disconnect the related component harness connectors.
- Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
- Proper connector installation.
- Damaged connector locks.
- Corrosion.
- Other signs of water intrusion.
- Weather seal damage (if equipped).
- Bent terminals.
- Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
- Terminals that have been pushed back into the connector cavity.
- Check for spread terminals and verify proper terminal tension.
Repair any conditions that are found.
- Connect all PCM harness connectors. Be certain that all harness connectors are fully seated and the connector locks are fully engaged.
- Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
- Connect all related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
- With the scan tool, erase DTCs.
- Test drive or operate the vehicle in accordance with the when monitored and set conditions.
- With the scan tool, read DTCs.
Did the DTC return?
Yes
- Replace and program the Powertrain Control Module (PCM) in accordance with the Service Information. Refer to MODULE, POWERTRAIN CONTROL (PCM), REMOVAL .
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
No
- The wiring or poor connection problem has been repaired.
- Perform the POWERTRAIN VERIFICATION TEST. Refer to POWERTRAIN VERIFICATION TEST .
NO RELATED
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:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.