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This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


OBD-II diagnostic trouble code P2097 indicates a fault with the post catalytic converter fuel trim system being too rich in bank 1  This code trigger when the downstream bank 1 oxygen sensors register a rich condition.


Fuel trim is the correction that the powertrain control module (PCM) makes to the mixture to maintain the required air/fuel ratio. In modern vehicles, there is one O2 sensor mounted upstream of the exhaust system and another one mounted downstream, these are referred to as sensor one and sensor two.

The powertrain control module (PCM) utilizes the second oxygen sensor to measure the un-combusted hydrocarbon molecules in the exhaust stream after it has passed the catalytic converter. If the engine is in perfect running condition, the catalytic converter should burn off any excess hydrocarbon molecules and the fuel trim should be within range. 

Oxygen sensors aid in this cycle by keeping the powertrain control module (PCM) updated on oxygen levels in the exhaust stream. This permits the PCM to adjust the air to fuel ratio whenever necessary. If the fuel trim is too rich, and the deviation from desired values exceeds a specified upper limit for a period of time set by the manufacturer, the PCM will set the code P2097. It will also illuminate a warning light along with activating the failsafe mode. The failsafe mode will stay until normal operation is found or the fault is resolved.


The possible causes for the error code P2097 could includes:

  • Burnt, damaged, disconnected, or corroded wiring and/or connectors
  • Damaged mass air flow or manifold air pressure sensor
  • Defective oxygen sensor
  • Failure of the catalytic converter
  • Exhaust leak near the downstream oxygen sensor
  • Fuel contamination


The symptoms can vary significantly due to various different causes:

  • Check Engine Light is illuminated
  • Lean condition
  • Rich condition
  • Decrease in engine performance
  • Decrease in fuel efficiency
  • Increased fuel consumption
  • Varying degree of power loss, depending on the application and the nature of the problem
  • Emissions of black smoke from the tail pipe
  • Poor, erratic, or rough idling
  • Engine may stumble upon acceleration
  • Sometimes you may notice a fuel odor
  • Vehicle may not pass an emission test


For the correct diagnosis and solution of the error code P2097, you should follow the steps mentioned beneath:

Step 1: Check the applicable Service Bulletins for your vehicle.

Step 2: The engine must be running efficiently before attempting to diagnosis this code. Any sort of ignition failure, throttle position sensor codes, mass air flow sensor codes should be addressed before attempting to diagnose a code P2097.

Step 3: Do a visual inspection of cables and connectors related to the system. If you find any wiring in bad condition or corroded connectors immediately repair or replace them, clear the code, and rescan the system to check whether the code returns.

Step 4: If the code persists but no visible damage to wiring or the sensor is found, use a Digital Volt Ohm Meter (DVOM) to check the resistance, ground signal, and voltage for the Oxygen Sensor circuit. Compare all obtained readings with the values stated in the manual, and make repairs, or replace wiring as required to ensure that all electrical values falls within the ranges specified by the manufacturer in the service bulletins.

NOTE: Disconnect the sensor from the PCM/ECM before performing resistance, ground, and/or continuity tests to prevent damaging the controller.

Step 5: Change the O2 Sensor if its measured resistance does not match with the value specified by the manufacturer.

Step 6: If the code comes up, but all the electrical values   comply with the specified values, remove the sensor from the application and do a visual inspection for any signs of oil contamination, or the existence of other harmful deposits.

Step 7: If the code still persists beyond step 6, there are two possibilities to consider. The first is that the catalytic converter itself is defective, or there are some sort of problems with the PCM. The latter possibility is rare, and will quite often be indicated by a code other than P2097, which leaves the catalytic converter as the most likely cause of this code.

Common mistakes

Common mistakes while diagnosing this error code are unnecessary and expensive replacements which usually happens when one doesn’t follow all the steps carefully. For this error code usually, people replace catalytic converter without properly diagnosing it, as the real fault may be in the oxygen sensor.

One should follow all the diagnosing steps in order to avoid expensive and unnecessary replacements. It is always recommended to seek the help of an experienced mechanic or technician to avoid any mistakes.

How serious is this?

The P2097 code can have no symptoms or might have an engine that will not run. If any drivability concerns are present, the vehicle should not be driven until the vehicle is fully repaired by a professional automobile mechanic.

What repairs can fix the code?

repair manualsrepair manuals

Similar to other OBD-II diagnostic trouble code, the repair process for the error code P2097 may differ based on the vehicle. Hence, once you’ve diagnosed the issue, make sure to research a solution that’s specific not only to what triggered the code but also to your vehicle make, year, and model.

Below mentioned are the few ways to fix the OBD Code P2097:

  • Reinstate the defaults in the powertrain control module
  • The malfunctioning oxygen sensor should be replaced or repaired as per the need
  • Carefully address the faults in the exhaust system parts
  • Recondition the non-functioning catalytic converter
  • Get the exhaust leak repaired or resolved

Related codes

P2096 – Post Catalyst Fuel Trim System Too Lean Bank 1

P2098 – Post Catalyst Fuel Trim System Too Lean Bank 2

P2099 – Post Catalyst Fuel Trim System Too Rich Bank 2


The OBD-II scanner error code P2097 can cause serious problem if not addressed for an extended period,. It might cause significant damage to your engine, oxygen sensors, PCM or other components of your vehicle. In latter cases, you may also find that an unfixed P2097 code can lead to the expensive replacements of engine components.P2097 CODE – WHAT DOES IT MEAN & HOW TO FIX IT