OBD Code P2BAD - NOx Exceedence - Root Cause Unknown

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The trouble code P2BAD can be elucidated as NOx Exceedance - Root Cause Unknown Issue. This code is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially those made from 1996 up to present. It’s also more common among Audi, Citroen, Chevrolet, Ford, Hyundai, Nissan, Peugeot, and Volkswagen vehicles. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model, powertrain configuration type, to another.

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Learn More About OBD Error Code P2BAD

If a NOx sensor fails, the vehicle can have multiple faults on the dashboard which will capture the power of your truck (Limp mode). As NOx sensors are directly linked to the SCR system, there will also be emission and general SCR system faults, which only add to the list of issues. Thus, when the PCM notes that the NOx sensor heater control circuit is not working properly, OBD code P2BAD may get flashed.


What causes this problem with the NOx Exceedance - Root Cause Unknown?


  • Faulty MAP (Manifold Absolute Pressure) sensor
  • Contaminated/Damaged MAF/VAF sensor
  • Damaged wiring or connectors that may be short or open
  • Breakage and leaky air inlet pipe
  • Problematic Engine Vacuum Pump
  • Faulty PCM that may require replacement or reprogramming
  • Poor electrical connections to the NOx sensor and circuit

Replace/Repair These Parts To Fix OBD Code P2BAD

  1. Exhaust Gas Recirculation Valve - Did you just see check engine light flashing on your dashboard? If the computer would detect some faults with the automobile’s EGR valve circuit, then it would set up the check engine light so that the driver is notified about the fault. Don’t waste time and get them replaced or else this fault code can turn up.
  2. Engine Control Module - Most of the time it is difficult to intercept the ECM faults and thus must be checked for thoroughly. There can be a problem with the circuit or the software might have malfunctioned. Thus repair, replace or reprogram the component as per requirement.
  3. Powertrain Control Module - If the PCM is faulty, it can store wrong OBD codes and can lead to misdiagnoses. This can happen due to misinterpretation of data received from the various sensors and components which also affects the vehicle’s performance. Thus, replace it immediately.
  4. Fuel Injector - Affected fuel injectors can cause reduced performance and throttle response. It can also affect the fuel economy and affect the engine emission. Thus, replace faulty fuel injector now!
  5. Diesel Exhaust Fluid Pump - The diesel exhaust fluid pump needs to work properly if the transmission system has to perform. If it is not functioning, the transmission may slip and cause harsh shifts too. Thus replace faulty pump now and buy a new one from us!
  6. Electronic Control Unit - If the ECU is at fault, it will not be able to read the boost converter temperatures correctly leading to under performance. Thus, replace faulty ECU now!
  7. Diagnostic Tool - Choose from our diagnostic tools collection that will come in handy to detect and correct the OBD error code.
  8. Mass Air Flow Sensor - Any problem with the MAF sensor can affect the engine performance and the system will not be able to manage the air to fuel ratio properly. Buy new MAF sensor now!
  9. Throttle Position Sensor - If the TPS is damaged or faulty, it will result in loss of engine power and acceleration along with reduced fuel economy. Replace it immediately, if faulty.
  10. Catalytic Converter - If the catalytic converter is damaged, it will affect the fuel delivery and the air intake system respectively. Also, it may result in increased emission from the exhaust. Thus, it becomes important to replace faulty catalytic converter immediately.
  11. Manifold Absolute Pressure Sensor - MAP sensor at fault can cause increased fuel consumption, lack of power and failing an emission test. Thus, replace it now!

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Symptoms Of OBD Error Code P2BAD

We at Parts Avatar Canada care for our customers, and that’s why we will help you to diagnose P2BAD code by listing out some major symptoms. They are mentioned below as follows


Common Symptoms


  • Loss of engine power and acceleration
  • Exhaust being rich and lean
  • Increased fuel consumption
  • Check engine light illuminated
  • Black smoke from exhaust pipe

How To Correct P2BAD NOx Exceedence - Root Cause Unknown

Learn the ways with which you can correct this trouble code:


  • Clean the MAF (Mass Airflow Sensor) with a safe electronic cleaner, if dirty.
  • Replace MAF (Mass Airflow Sensor), if found faulty.
  • Replacement of damaged MAP (Manifold Absolute Pressure Sensor)
  • Check for any vacuum pump and air intake pipe leakages/damages. Replace faulty/broken/open/short wiring and connectors to the NOx sensors and circuits.

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Vehicles Frequently Showing P2BAD OBD Code

P2BAD Acura OBD Error Code

P2BAD Honda OBD Error Code

P2BAD Mitsubishi OBD Error Code

P2BAD Audi OBD Error Code

P2BAD Hyundai OBD Error Code

P2BAD Nissan OBD Error Code

P2BAD BMW OBD Error Code

P2BAD Infiniti OBD Error Code

P2BAD Porsche OBD Error Code

P2BAD Buick OBD Error Code

P2BAD Jaguar OBD Error Code

P2BAD Saab OBD Error Code

P2BAD Cadillac OBD Error Code

P2BAD Jeep OBD Error Code

P2BAD Scion OBD Error Code

P2BAD Chevrolet OBD Error Code

P2BAD Kia OBD Error Code

P2BAD Subaru OBD Error Code

P2BAD Chrysler OBD Error Code

P2BAD Lexus OBD Error Code

P2BAD Toyota OBD Error Code

P2BAD Dodge OBD Error Code

P2BAD Lincoln OBD Error Code

P2BAD Vauxhall OBD Error Code

P2BAD Ford OBD Error Code

P2BAD Mazda OBD Error Code

P2BAD Volkswagen OBD Error Code

P2BAD GMC OBD Error Code

P2BAD Mercedes OBD Error Code

P2BAD Volvo OBD Error Code

Easy Diagnosis Of Engine Error OBD Code P2BAD

It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P2BAD code to be stored:


  • P2BAD is properly diagnosed with an advanced scan tool capable of factory sensor readings (not just one from an auto parts store). A qualified technician can read the data from the advanced scan tool to determine when the problem occurred, or if it is still occurring. They may clear the code/light and test drive the vehicle while monitoring the scan tool data to see if the fault returns or is present.
  • Based upon the conditions of the test, possibly clearing the code, and road testing the car while monitoring the data, further diagnosis may be required. Diagnosis may require multiple tools such as:
  • A technician typically begins by hooking the vehicle up to an OBD-II scanner in order to verify that the code is present, and check for other codes.
  • This data along with freeze frame data is recorded, and the codes are then cleared to see if they reoccur.
  • Next, there should be a visual inspection of the wiring and connectors to check for loose connections, corrosion, or shorts.
  • Replacement of Damaged wiring/connections to the MAF (Mass Air Flow) and NOx Sensor and circuits.
  • Inspect for faults in the fuel pump and filter, EGR valve and O2 sensor and circuit and do the necessary replacements as well.
  • Check for faulty DPF and DEF pump that may have mechanical failures and might need replacement.
  • Repair faulty PCM sensor that may require reprogramming.
  • Replace Leaky and damaged intake/inlet pipe immediately.
  • Faulty MAF (Mass Airflow Sensor) needs replacement as it directly hampers the engine performance.

Common Mistakes When Diagnosing the P2BAD Code


  • Always tale help of a qualified technician with experience to counter the OBD code errors. Use professional factory grade scanning and diagnostic tools to diagnose this problem.
  • Missing the diagnosis steps leading to misdiagnosis and error to return
  • Though the most common cause is a clogged fuel filter, it will not be a necessary problem for all vehicles. Thus, proper inspection needs to be done
  • It is important to follow the steps so unnecessary repairs are not performed wasting time and money. Never forget to check for faulty or damaged wiring and connections as they can be the reason for the OBD error code and can be a cheap solution to the problem.

Other Diagnostic Codes Related To OBD Code P2BAD