P2096

P2096-DOWNSTREAM FUEL TRIM SYSTEM 1 LEAN







- When Monitored:
With the engine running in closed loop mode, the ambient/battery temperature above (-7°C) 20°F, altitude below 8500 ft.

- Set Condition:
If the Powertrain Control Module (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 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. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC

NOTE: Check the vehicle repair history. If the 1/2 O2 has been replace 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.

1. Ignition on, engine not running.
2. With a scan tool, read the DTCs.

Is the DTC active at this time?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test.

2. CHECKING THE EXHAUST SYSTEM FOR LEAKS
1. Perform the diagnostic procedure for CHECKING THE EXHAUST SYSTEM FOR LEAKS. 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 3

3. CHECKING THE FUEL DELIVERY SYSTEM
1. Perform the diagnostic procedures for FUEL PRESSURE LEAK DOWN and FUEL DELIVERY SYSTEM OUTPUT - FLOW TEST. Fuel Pressure Leak Down Fuel Delivery System Output - Flow Test.

Were any problems found?

Yes

- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 4

4. ENGINE MECHANICAL PROBLEM
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 5

5. O2 SENSOR




1. Ignition on, engine not running.
2. Disconnect the 1/2 O2 Sensor harness connector.
3. With the scan tool, monitor the 1/2 O2 Sensor voltage.
4. The O2 Sensor voltage should read 5.0 volts on the scan tool with the connector disconnected.
5. Using a jumper wire, jump the (K141) O2 Sensor 1/2 Signal circuit to the (K902) O2 Downstream Return circuit in the O2 Sensor harness connector.

NOTE: The voltage should drop from 5.0 volts to 2.5 volts with the jumper wire in place.

Did the O2 Sensor volts change from 5.0 volts to 2.5 volts?

Yes

- Replace the O2 Sensor.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 6

6. (K141) O2 SENSOR 1/2 SIGNAL CIRCUIT
1. Remove the jump wire.
2. Ignition on, engine not running.
3. With the scan tool, monitor the 1/2 O2 Sensor voltage.

Is the voltage above 4.8 volts?

Yes

- Go To 7

No

- Check the (K141) O2 Sensor 1/2 Signal circuit for 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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

7. (K299) O2 SENSOR 1/2 HEATER CONTROL CIRCUIT




1. Turn the ignition off.
2. Measure the resistance between ground and the (K299) O2 Sensor 1/2 Heater Control circuit in 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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Go To 8

8. (K902) O2 DOWNSTREAM RETURN CIRCUIT




1. Measure the voltage on the (K902) O2 Downstream Return circuit in the O2 Sensor harness connector.

Is the voltage at 2.5 volts?

Yes

- Check the fuel system for contaminants.
- Perform the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.

No

- Check the (K902) O2 Downstream Return 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 the POWERTRAIN VERIFICATION TEST. Powertrain Verification Test.