P0175
P0175-FUEL SYSTEM 2/1 RICH
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The fuel feedback system will maintain a stoichiometric air/fuel mixture, 14.7:1, by modifying the injector pulse width according to the oxygen content of the exhaust gas. The Powertrain Control Module (PCM) makes short term and long term fuel corrections to maintain stoichiometric air/fuel ratio for best Catalytic Converter efficiency. If one or more cylinders do not operate at stoichiometric then the high frequency content of the O2 Sensor will increase. Short term fuel correction is based on Upstream O2 Sensor output and is designed for quick engine response. The long term fuel correction compensated for variations in the engine specifications, sensor tolerances and component aging and is designed to correct rich and lean conditions over a longer period of time.
- When Monitored:
With the engine running in closed loop mode, the ambient/battery temperature above -6.7°C (20°F) and altitude below 2590.8 m (8500 ft).
- Set Condition:
If the Powertrain Control Module (PCM) multiplies short term compensation by long term adaptive and a purge fuel multiplier and the result is below a certain value for 30 seconds over two trips, a freeze frame is stored, the MIL illuminates and a trouble code is stored. Two Trip Fault. Three good trips to turn off the MIL.
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. PCM Pre-Diagnostic Troubleshooting Procedure.
Diagnostic Test
1. ACTIVE DTC
1. Diagnose all other DTCs before continuing.
NOTE: Check for contaminants that may have damaged an O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.
2. Start the engine.
3. Allow the engine to reach normal operating temperature.
4. With the scan tool, read DTCs.
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 at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. PCM Intermittent Condition Test.
2. CHECK THE FUEL DELIVERY SYSTEM
1. Perform the CHECKING THE FUEL DELIVERY SYSTEM test procedure. Checking The Fuel Delivery System.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 3
3. CHECK THE EXHAUST SYSTEM FOR LEAKS
1. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS test procedure. Checking The Exhaust System For Leaks.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 4
4. CHECK THE OXYGEN SENSOR OPERATION
1. Perform the CHECKING THE OXYGEN SENSOR OPERATION test procedure. Checking The Oxygen Sensor Operation.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 5
5. O2 SENSOR 2/1 HEATER OPERATION
1. Turn the ignition off.
NOTE: Wait a minimum of 10 minutes to allow the O2 Sensor to cool down before continuing the test. Allow the O2 Sensor voltage to stabilize at 5.0 volts.
2. Ignition on, engine not running.
3. With the scan tool, actuate the O2 Sensor 2/1 Heater Test.
4. Using the scan tool, monitor O2 Sensor 2/1 voltage for at least two minutes.
Does the voltage stay above 4.5 volts?
Yes
- Verify that there is good pin to terminal contact in the O2 Sensor 2/1 and Powertrain Control Module connectors. Replace the O2 Sensor 2/1 if no problems were found with the connectors. Oxygen Sensor - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 6
6. CHECK THE MAP SENSOR OPERATION
1. Perform the CHECKING THE MAP SENSOR OPERATION test procedure. Testing and Inspection.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 7
7. CHECK THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION
1. Perform the CHECKING THE ENGINE COOLANT TEMPERATURE SENSOR OPERATION test procedure. Checking The Engine Coolant Temperature Sensor Operation.
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Go To 8
8. EVAP PURGE SOLENOID OPERATION
1. Turn the ignition off.
2. Disconnect the hoses at the Evap Purge Solenoid.
3. Using a hand vacuum pump, apply 1.0 in. Hg. to the "ENGINE" side of the Evap Purge Solenoid.
NOTE:
The solenoid should hold vacuum for a minimum of 15 seconds.
Did the Evap Purge Solenoid hold vacuum?
Yes
- Go To 9
No
- Verify that there is good pin to terminal contact in the Evap Purge Solenoid and Powertrain Control Module connectors. Replace the Evap Purge Solenoid if no problems were found with the connectors. Evap Purge Solenoid - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
NOTE: Connect the vacuum hoses before continuing.
9. ENGINE MECHANICAL
1. Turn the ignition off.
2. Check for any of the following conditions/mechanical problems:
- AIR INDUCTION SYSTEM - must be free from leaks.
- ENGINE VACUUM - must be at least 13 inches in neutral
- ENGINE VALVE TIMING - must be within specifications
- ENGINE COMPRESSION - must be within specifications
- ENGINE EXHAUST SYSTEM - must be free of any restrictions or leaks.
- ENGINE PCV SYSTEM - must flow freely
- TORQUE CONVERTER STALL SPEED - must be within specifications
- POWER BRAKE BOOSTER - no internal vacuum leaks
- FUEL - must be free of contamination
- 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. Powertrain Verification Test.
No
- Go To 10
10. POWERTRAIN CONTROL MODULE (PCM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Sensors and the Powertrain Control Module (PCM).
- Look for any chafed, pierced, pinched or partially broken wires.
- Look for broken, bent, pushed out or corroded terminals.
- Verify that there is good pin to terminal contact in the O2 Sensor 1/1 and Powertrain Control Module connectors.
- Perform any Technical Service Bulletins that may apply.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.
No
- Replace and program the Powertrain Control Module. Powertrain Control Module - Removal.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.