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P2099 OBD-II Trouble Code: Post Catalyst Fuel Trim System Too Rich Bank 2

Check Engine Light

P2099 code definition

Post catalyst fuel trim system too rich bank 2

What the P2099 code means

This trouble code indicates that the powertrain control module is malfunctioning in its ability to control fuel trims. Fuel trims are what the powertrain control module uses to determine whether to add fuel or remove fuel in order to keep the air/fuel ratio correct for that particular vehicle.

What are the causes of the P2099 code?

Some potential causes of this trouble code may include:

  • The mass air flow sensor could be malfunctioning

  • The mass air flow sensor’s circuitry could be damaged

  • The air inlet tubing connected to the intake manifold could have a vacuum leak allowing unmetered air to enter the engine

  • The oxygen sensor(s) or circuitry could be damaged

  • Anything that could cause a rich condition, such as a faulty fuel pressure regulator or manifold absolute pressure sensor

  • The powertrain control module could be malfunctioning

What are the symptoms of the P2099 code?

Symptoms of this trouble code that the driver may experience would include:

  • The vehicle may not accelerate properly
  • The vehicle may emit black smoke upon acceleration or start up
  • The Check Engine Light will be illuminated
  • The engine may lack sufficient power
  • The engine may stall at times
  • The vehicle will have poor fuel economy
  • It is possible that this code could cause no symptoms at all other than the Check Engine Light

How does a mechanic diagnose the P2099 code?

A mechanic may start diagnosing this issue by using an OBD-II scanner to verify the fuel trims. At this point, the mechanic would then visually inspect the air intake system of the engine to make sure that all parts are in good condition and are working properly, paying close attention to the mass air flow sensor. If the problem is not found here, the mechanic would then go under the vehicle to inspect the fuel and exhaust systems.

During this inspection, the mechanic would check the fuel pressure regulator and the oxygen sensors for proper function. The manifold absolute pressure sensor would also be checked at this time. If the problem still has not been confirmed, the mechanic would then use a high tech scan tool to test the powertrain control module using the manufacturer’s recommended procedure.

Once the cause of the problem has been identified, the mechanic would relay all his/her findings over to the customer and recommend the correct repair. At this point, it would be left up to the customer to make a repair decision.

Common mistakes when diagnosing the P2099 code

A common mistake when diagnosing any fuel trim code would be to replace the mass air flow sensor without testing it since it is the most common cause of fuel trim codes. It is very important to utilize all diagnostic material available to you in order to diagnose Check Engine Lights correctly. Check Engine Lights are the most common cause of misdiagnosis of any system on the vehicle.

How serious is the P2099 code?

The seriousness of this issue depends on the amount and severity of the symptoms that are associated with it. If the engine does not run properly and is causing the driver to be late to work or stranded on the side of the road, I would consider this code to be serious. If this code does not have any symptoms associated with it other than a Check Engine Light, this code would be low on the seriousness scale. It is important to note, however, that if a fuel trim code is stored for a long period of time, damage to the catalytic converters may result.

What repairs can fix the P2099 code?

Repairs that can fix this trouble code may include:

Additional comments regarding the P2099 code

Although this code is not very serious, if no symptoms are associated with it, it is still important to note that small damages can lead to larger damages. Catalytic converters can be a lot more costly than some of the sensors that could potentially be causing this trouble code. It is best to have the issue diagnosed and repaired as soon as possible even if no symptoms exist. This will help prevent further damage to the vehicle’s powertrain.

Need help with a P2099 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230

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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