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P2198 Code – What Does It Mean & How To Fix It

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.


P2198 is an OBD-II Code that refers to O2 Sensor Signal Stuck Rich Bank 2 Sensor 1


A P2198 code is caused by an ECM (Engine Control Module) receiving a signal from the sensor readings that are beyond the range it can accept. The ECM interprets this as a fault inside either O2 Sensor System Bank 2 Sensor 1, or the part of the circuit that controls the mixture is defective. The ECM will then store the code and turn on the MIL (Malfunction Indicator Light)


Common causes for this code include:

  • Faulty O2 Sensor
  • Faulty O2 Control System
  • Failed/Faulty Mixture Control Solenoid
  • Vacuum leak
  • Faulty Fuel Injector
  • Wrong fuel pressure
  • Exhaust leak


The symptoms of a P2198 code are:

  • The Check Engine Light comes on
  • Poor fuel mileage
  • Engine will run rich 


To diagnose a P2198 DTC code, a technician would:

  1. Scan for codes in the ECM and look at the freeze frame data for failure.
  2. Check O2 Sensor heater circuits for shorts or opens.
  3. Ensure battery voltage is present at the mixture control solenoid connector.
  4. Confirm that engine RPM does not change with accelerator pedal position.
  5. Test fuel pressure to ensure proper pressures are reached and that no leaks exist in the system. 
  6. Low engine RPM alone could be a sign of serious internal engine damage, so if necessary, rule out other possible causes first before jumping to this conclusion.

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a P2198 code:

  • Failing to properly diagnose the problem before replacing parts.
  • Replacing parts without first checking for other issues that could be the root cause of the DTC.
  • Not verifying if engine RPM changes with accelerator pedal position.
  • Not checking battery voltage at mixture control solenoid connector.
  • Not checking O2 sensor heater circuits for shorts or opens.
  • Not verifying proper fuel pressures and no leaks in the system.

How serious is this?

A P2198 code is mostly an inconvenience, but the possible consequences it can lead to are:

  • Engine damage due to running too rich.
  • Emission problems if not repaired in a timely manner. 
  • Stalling of the engine due to faulty mixture control solenoid or O2 sensors. 
  • Malfunctioning catalyst system which may cause increased emissions and poor fuel economy

What repairs can fix the code?

The following are solutions that may fix this problem:

  1. Replace Fuel Injector 
  2. Replace Mixture Control Solenoid 
  3. Check Fuse Box
  4. Replace Air Mass Meter (if equipped) 
  5. Repair vacuum hoses and hoses/tubing where necessary based on previous testing/observations
  6. Replacing fuel system components, such as fuel pump, filter, and pressure regulator to ensure proper pressures are reached and no leaks exist in the system.
  7. Checking wiring for shorts or opens

Related codes

A P2198 is related to and may be accompanied by the following codes:

P0171 – System too Lean

P0174 – System too Rich

P1143 – Fuel Trim Malfunction Bank 1 

P1149 – Fuel Trim Malfunction Bank 2


In conclusion, the P2198 code is a generic trouble code that means the computer has detected an issue with the O2 Sensor Signal Stuck Rich Bank 2 Sensor 1 and is due to a signal that is not within an acceptable range. The most common causes include Faulty O2 Sensor, Faulty O2 Control System or Mixture Control Solenoid. Other possible causes include Vacuum leak, Faulty Fuel Injector and Wrong fuel pressure. When diagnosing this code it is important to check if engine RPM changes with accelerator pedal position and ensure battery voltage is present at the mixture control solenoid connector. It may be necessary to rule out other possible causes before jumping to conclusions so as not to damage parts needlessly.