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P2098 OBD-II Trouble Code: Post Catalyst Fuel Trim System Too Lean Bank 2

Check Engine Light

What the P2098 code means?

P2098 is an OBD-II generic code for the engine control module (ECM) detecting the post catalyst O2 sensor fuel trim is testing too lean on a two trip minimum to set the code.

What causes the P2098 code?

  • The ECM is detecting the pre catalyst O2 sensor not working correctly and then monitors the post catalyst O2 sensor to see if the problem correlates to the pre catalyst O2 sensor on a two trip requirement.

  • The exhaust may have a leak or engine problem before the pre catalyst sensor.

  • The engine may have mechanical or fuel related issues causing the code.

  • The O2 sensor wiring or sensor is the failure.

What are the symptoms of the P2098 code?

  • The Check Engine light will be illuminated and the code is set in ECM memory as a fault after the two trips are completed back to back.

  • The ECM will go into failure mode for fuel control. This may cause lean or rich drive symptoms depending on the manufacture failure mode strategy.

  • If the problem goes away then the engine will go back to operating normal again, but will keep the Check Engine light on till it is cleared.

How does a mechanic diagnose the P2098 code?

  • Scans for codes and documents the code in the ECM and looks at the freeze frame data for failure.

  • Scans the ECM to see if the O2 sensors are indicating a problem on one or both sides of the engine. Notes to clear the code to get the engine out of failure mode fuel strategy.

  • Checks the engine for exhaust leaks, O2 sensor or wiring damage.

  • Checks the engine for any other codes that may cause the O2 sensors to fail.

Common mistakes when diagnosing the P2098 code?

  • Clearing ECM memory codes before checking the freeze frame data for the main failure problem, so the failure may be duplicated and repaired

  • Failing to clear the ECM codes to properly test the O2 sensors out of failure mode

  • Failing to verify and correct any exhaust leaks or other problems that may cause the code P2098

  • Failing to verify the O2 sensor operation is normal after the repairs are done

How serious is the P2098 code?

Code P2098 is a code indicating the ECM cannot control the fuel as it needs to since the O2 sensor is not giving the fuel control closed loop control it needs to control the fuel correctly.

What repairs can fix the P2098 code?

  • Clearing the code and repairing the exhaust leak

  • Replacing the pre catalyst O2 sensor or repair the wiring

  • Replace O2 sensors for the pre and post catalyst if they are damaged from an issue that has got repaired like a head gasket that leaked coolant into the exhaust

Additional comments for consideration regarding the P2098 code

Code P2098 will come on only after the ECM has detected the problem to happen for two complete drive cycles. The most common problem is an exhaust leak at the exhaust manifold gasket or flange. The repair of the exhaust may fix the code from coming back.

Need help with a P2098 code?

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The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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