P2096
P2096-DOWNSTREAM FUEL TRIM SYSTEM 1 LEAN
For complete wiring diagrams refer to Diagrams/Electrical.
- 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 PCM multiplies short term compensation by long term adaptive as well as a purge fuel multiplier and the result is below a certain value for a calibratable amount of time 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.
Diagnostic Test
1. ACTIVE DTC
NOTE: Check the vehicle repair history. If the 1/2 O2 has been replaced make sure that the O2 sensor was properly installed and meets OEM specification.
NOTE: Check for contaminants that may have damaged the O2 Sensor: contaminated fuel, unapproved silicone, oil and coolant.
Start the engine.
Allow the engine to reach normal operating temperature.
With a scan tool, select View 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
- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition
2. CHECKING THE EXHAUST SYSTEM FOR LEAKS
Turn the ignition off.
Raise the vehicle.
WARNING: The normal operating temperature of the exhaust system is very high. Never work around or attempt to service any part of the exhaust system until it has cooled. Special care should be taken when working near the catalytic converter. The temperature of the converter rises to a high level after a short period of engine operating time
Connect Exhaust Cone #8404-EC or #8404-EC to Air Pressure Regulator (with hose) #W-18-MIL-1146AS.
CAUTION: The air pressure must not exceed 27.6 kPa (4 psi), otherwise engine damage can occur.
Attach shop air to the air pressure regulator.
Adjust the Air Pressure Regulator to 27.6 kPa (4 psi)
Insert the exhaust cone into the vehicle tail pipe.
If the vehicle is equipped with dual exhaust. Use the #8404-ECT with equipped attached plug, plug one side of the dual exhaust pipe. Pressurize the other as described above.
Apply SNOOP leak finder liquid or a mixture of liquid dish soap and water to the following areas:
- All welded joints from the exhaust manifold to 152.4 mm (6 inches) behind the downstream O2 sensor
- O2 sensor seal points
- O2 sensor boss welds
- Flange/joint connection(s)
- Exhaust manifold to cylinder head connection(s)
- EGR solenoid gasket base and tube seal points (if equipped)
Watch for the liquid/soapy water to bubble.
Use the following definitions to help determine if system or component repair/replacement is necessary:
Type 1 Leak is defined as a leak where very small foam like bubbles 1 mm (0.04 of an inch) or less appear.
Any Type 1 or greater leaks found in welded joints, O2 sensor seal points or O2 sensor boss welds must be repaired or the component must be replaced.
Type 2 Leak is defined as a leak where larger bubbles pea size, 8 mm (0.3 of an inch) or greater appear.
Any Type 2 or greater leaks found in flange or joint connections, exhaust manifold to cylinder head connections, or EGR gasket and tube seal points must be repaired or the components must be replaced
If a leak is found that matches the above definition, repair or replace the component as necessary.
Once the repair is complete, repeat the procedure to verify that all leaks have been repaired.
Were any exhaust leaks found?
Yes
- Repair or replace the leaking exhaust parts as necessary.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 3
3. ENGINE MECHANICAL
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 POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 4
4. O2 SENSOR
Ignition on, engine not running.
Disconnect the 1/2 O2 Sensor harness connector.
With the scan tool, monitor the 1/2 O2 Sensor voltage.
The O2 Sensor voltage should read between 4.1 and 5.0 volts on the scan tool with the connector disconnected.
Using a jumper wire, jump the (K141) O2 Sensor 1/2 Signal circuit to the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.
NOTE: The voltage should drop from between 4.1 and 5.0 volts to 2.5 volts with the jumper wire in place.
Did the O2 Sensor volts change from between 4.1 and 5.0 volts to 2.5 volts?
Yes
- Replace the O2 Sensor
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 5
5. (K141) O2 SENSOR 1/2 SIGNAL CIRCUIT
Remove the jump wire.
Ignition on, engine not running.
With the scan tool, monitor the 1/2 O2 Sensor voltage.
Is the voltage between 4.1 and 5.0 volts?
Yes
- Go To 6
No
- Check the (K141) O2 Sensor 1/2 Signal circuit for a short to ground, an open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
6. (K299) O2 SENSOR 1/2 HEATER CONTROL CIRCUIT SHORTED TO GROUND
Turn the ignition off.
Disconnect the C3 PCM harness connector.
Measure the resistance between ground and the (K299) O2 Sensor 1/2 Heater Control circuit from the O2 Sensor harness connector.
Is the resistance below 5.0 ohms?
Yes
- Repair the short to ground in the (K299) O2 Sensor 1/2 Heater Control circuit.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Go To 7
7. (K904) O2 RETURN DOWNSTREAM CIRCUIT
Measure the voltage on the (K904) O2 Return Downstream circuit in the O2 Sensor harness connector.
Is the voltage at 2.5 volts?
Yes
- Check the fuel system for contaminants.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test
No
- Check the (K904) O2 Return Downstream circuit for a short to ground, open, or short to voltage. Inspect the O2 Sensor connector and the PCM harness connector. If OK, replace and program the Powertrain Control Module.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test