P2097-DOWNSTREAM FUEL TRIM SYSTEM 1 RICH

For a complete wiring diagram, refer to the Wiring Information.

When Monitored:
With the engine running in closed loop, the ambient/battery temperature above -7° C (20° F) and altitude below 8500 ft.
Set Condition:
The conditions that cause this diagnostic to fail is when the upstream O2 sensor becomes biased from an exhaust leak, O2 sensor contamination, or some other extreme operating condition. The downstream O2 sensor is considered to be protected from extreme environments by the catalyst. The Powertrain Control Module (PCM) monitors the downstream O2 sensor feedback control, called downstream fuel trim, to detect any shift in the upstream O2 sensor target voltage from nominal target voltage. The value of the downstream fuel trim is compared with the rich thresholds. Every time the value exceeds the calibrated threshold, a fail timer is incremented and mass flow through the exhaust is accumulated. If the fail timer and accumulated mass flow exceed the fail thresholds, the test fails and the diagnostic stops running for that trip. If the test fails on consecutive trips, a DTC is set.

POSSIBLE CAUSES
EXHAUST LEAK
FUEL DELIVERY SYSTEM
O2 SENSOR, WIRING, OR CONNECTORS
ENGINE MECHANICAL SYSTEM
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

1. EXHAUST LEAK

NOTE: A thorough exhaust leak test must be completed before removing an O2 Sensor or any other part from the exhaust system. Do not remove any parts before an exhaust leak check has been completed.

NOTE: An exhaust leak may cause downstream fuel adaptives to rail out, resulting in a false O2 Sensor failure

1.	Perform the diagnostic procedure for CHECKING THE EXHAUST SYSTEM FOR LEAKS. (Refer to 29 - Non-DTC Diagnostics/Drivability - Gas - Diagnosis and Testing) .

Were any problems found?

Yes

Go To 7

Go To 2

2. DTC IS ACTIVE

1.	Diagnose and repair any other active component or circuit DTCs before continuing with this procedure.

2.	Turn the ignition on.

3.	With the scan tool, select View DTCs. Copy DTC and Freeze Frame information.

4.	Start the engine and allow it to reach operating temperature.

WARNING:

When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing. Failure to follow these instructions may result in possible serious or fatal injury.

NOTE: Attempt to operate the vehicle under conditions similar to which the DTC was set.

NOTE: It may be necessary to test drive the vehicle within the DTC monitoring conditions in order for this DTC to set.

5.	With a scan tool, select View DTCs.

Is the status Active for this DTC?

Yes

Go To 3

Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

3. CHECKING THE FUEL DELIVERY SYSTEM

1.	Perform the diagnostic procedures for FUEL PRESSURE LEAK DOWN and FUEL DELIVERY SYSTEM OUTPUT - FLOW TEST. (Refer to 29 - Non-DTC Diagnostics/Drivability - Gas - Diagnosis and Testing) .

Were any problems found?

Yes

Repair as necessary in accordance with the Service Information.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 4

4. CHECKING THE OXYGEN SENSOR OPERATION

1.	Perform the diagnostic procedure for CHECKING THE OXYGEN SENSOR OPERATION. (Refer to 29 - Non-DTC Diagnostics/Drivability - Gas - Diagnosis and Testing) .

Were any problems found?

Yes

Repair as necessary in accordance with the Service Information.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 5

5. CHECKING THE ENGINE MECHANICAL SYSTEM

1.	Perform the diagnostic procedure for CHECKING THE ENGINE MECHANICAL SYSTEM. (Refer to 29 - Non-DTC Diagnostics/Drivability - Gas - Diagnosis and Testing) .

Were any problems found?

Yes

Repair as necessary in accordance with the Service Information.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Go To 6

6. POWERTRAIN CONTROL MODULE (PCM)

Using the wiring diagram/schematic as a guide, inspect the wiring and connectors relative to the components tested in this procedure.

Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Monitor the scan tool data relative to the components tested in this procedure and wiggle test the wiring and connectors.
Look for the data to change or for a DTC to set during the wiggle test.
Perform any technical service bulletins that may apply.

Were any problems found?

Yes

Repair as necessary.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

Replace and program the PCM in accordance with the Service Information.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

7. EXHAUST LEAK

1.	Repair the exhaust leak(s) as necessary.

2.	Start the engine and allow it to reach operating temperature.

3.	Test drive the vehicle at a steady 80 kph (50 mph) to 97 kph (60 mph) for at least 10 minutes.

4.	Stop the vehicle and turn the ignition off for 5 seconds.

5.	Test drive the vehicle again at a steady 80 kph (50 mph) to 97 kph (60 mph) for at least 10 minutes.

6.	Stop the vehicle.

7.	With the scan tool, select View DTCs.

Does this DTC reset as a pending or stored DTC?

Yes

Retest. Go To 1

Test Complete.
Perform the PCM VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).

P2097-DOWNSTREAM FUEL TRIM SYSTEM 1 RICH

P2097-DOWNSTREAM FUEL TRIM SYSTEM 1 RICH

POSSIBLE CAUSES