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Auto ... 2/22/2018

2016 Audi A6 Luxury 4 Cyl 1.80L

Preventive Maintenance

How do I diagnose P2099 OBD-II Trouble Code of my car and what are its causes?

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PartsAvatar Ca

PartsAvatar Ca 2/22/2018

What the P2099 code means?

This trouble code indicates that the power train control module is malfunctioning in its ability to control fuel trims. Fuel trims are what the power train 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?

Faulty bank 2 catalytic converter
A faulty mass air flow or manifold air pressure sensor
Defective bank 2 O2 sensor/s
Burnt, chafed, broken, or disconnected wiring

What are the symptoms of the P2099 code?

Symptoms for this code can vary greatly, due to its generality. Negative fuel trim indicates that the PCM is attempting to lean the air/fuel mixture and a positive fuel trim indicates that the PCM is attempting to richen it. Symptoms can include just a service engine soon lamp, poor acceleration, a hesitation or misfire upon acceleration or at start up, engine stall at start up, black smoke upon acceleration (or at start up), sub-par fuel economy, or there may be no symptoms at all. Some code setting conditions can lead to engine and/or catalytic converter damage if left unattended over a long period of time.

Common mistakes when diagnosing the P2099 code:

Technicians report that this code rarely occurs without the accompaniment of other fuel system codes. This code is rarely exhibited in vehicles that are not manufactured in Europe. Failure to diagnose other codes, before diagnosing this code, can lead to a misdiagnosis.

What repairs can fix the P2099 code?

1. Replace the mass air flow sensor
2. Repair or replace circuitry for the mass air flow sensor
3. Replace the manifold absolute pressure sensor or circuitry associated with it.
4. Replace the fuel pressure regulator
5. Replace the power train control module


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