P2097

DTC P2097

Circuit Description

The bank 1 sensor 2 or bank 2 sensor 2 heated oxygen sensor (HO2S) output signal is used by the engine control module (ECM) when calculating the oxygen storage capacity (OSC) of the three-way catalytic converter (TWC). The ECM can also use each HO2S voltage signal to calculate the air-fuel ratio that results in the most efficient operation of the TWC. This accomplished by minor fuel trim corrections, rich or lean, based on the output signal received from the HO2S. The ECM will adjust the air-fuel ratio in an attempt to keep the bank 1 sensor 2 and bank 2 sensor 2 output signals near 600 mV. If the ECM continues to make a lean fuel trim correction for longer than a calibrated time, in an effort to drive the post sensor near 600 mV in response to a rich engine operating condition, DTC P2097 will set for bank 1 or DTC P2099 will set for bank 2.

DTC Descriptor

This diagnostic procedure supports the following DTCs:

^ DTC P2097 Post Catalyst Fuel Trim System High Limit Bank 1
^ DTC P2099 Post Catalyst Fuel Trim System High Limit Bank 2

Conditions for Running the DTC

^ DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0101, P0102, P0103, P0106, P0107, P0108, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0128, P0131, P0132, P0135, P0137, P0138, P0139, P0140, P0141, P0151, P0152, P0155, P0157, P0158, P0159, P0160, P0161, P0201-0208, P0300, P0301-0308, P0442, P0443, P0446, P0449, P0453, P0454, P0455, P0458, P0459, P0496, P2231, P2234, P2237, P2240, P2243, P2247, P2251, P2254, P2626, P2629 are not set.
^ The canister purge is in a steady state.

Conditions for Setting the DTC

The ECM has commanded the fuel trim less than -2.93 percent for more than 24 seconds out of a 25 second monitoring period.

OR

The affected bank HO2S voltage is more than 845 mV for more than 75 seconds.

Action Taken When the DTC Sets

^ The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

^ Carefully inspect for any exhaust leaks between the upstream and downstream sensor of the affected bank.
^ The most likely cause for this DTC is a deteriorated or contaminated HO2S 1.
^ Depending on the state of HO2S deterioration, this code may not reset, or may be very difficult to reset.
^ If the HO2S deterioration is significant enough, other HO2S DTCs may set or be present in concurrence with this DTC.
^ Attempt to compare the activity of both the affected bank HO2S 1 and HO2S 2 to the known good bank using the live plot feature of the scan tool. Operate the vehicle under various load and vehicle/engine speed conditions. Look for any indication of improper operation or contamination of the affected bank HO2S 1 or HO2S 2.