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P209A OBD Error Code: Problem & Solutions

OBD CODE P209A - Reductant Injection Air Pressure Sensor B Circuit

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If the Check Engine Light illuminating on the dashboard? Are you experiencing reduced engine performance along with affected fuel economy? Is there black smoke emitting from the exhaust pipe? All these are the indications of increased emissions and affected exhaust system which in this case can be due to bad reductant injection air pressure sensor for B circuit, thus causing OBD code P209A to get stored in the Powertrain Control Module.

The OBD code P209A means Reductant Injection Air Pressure Sensor B Circuit Issue.

Learn More About OBD Error Code P209A

Usually, this type of error code gets stored in the system when the PCM notes that the voltage signal from the reductant injection air pressure sensor is out of limits. This can be due to various mechanical faults in various related components. When the error occurs due to the voltage signal output from the specific circuit B of the particular sensor, the OBD code P209A gets stored in the PCM.


What causes this problem with the Reductant Injection Air Pressure Sensor B Circuit?


  • Bad Reductant Injection Air Pressure Sensor
  • Wiring and harness for Reductant Injection Air Pressure Sensor is open or short
  • Poor electrical connections to Reductant Injection Air Pressure Sensor circuit
  • SCR controller/PCM or programming error

Replace/Repair These Parts To Fix Code P209A

  1. Engine Control Module - It is not always the components, but the ECM that can also be faulty. It can cause misinterpretation of correct data thus leading to wrong operational decisions which will affect the transmission and overall engine performance. Thus, replace faulty module and reprogram it now!
  2. Powertrain Control Module - Powertrain Control Module can also be faulty in rare cases and thus needs through checks for system and software errors. Thus check and replace it, if required.
  3. Diagnostic Tool - It is always advisable to use correct tools and equipment while resolving any OBD code issue as even small mistakes can lead to wrong diagnosis. Thus, always take help from a professional who has the knowledge and experience to such tools in efficient manner. Buy new quality diagnostic tools from us today!
  4. Electronic Control Unit - ECU monitors the temperature differences in the boost converter with the help of the temperature sensors to prevent the converter from overheating and malfunctioning. Thus, replace faulty ECU immediately.
  5. Exhaust Gas Recirculation Valve - Did you just see check engine light flashing on your dashboard? If the computer would detect some fault 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.
  6. 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!

Symptoms Of The OBD Error Code P209A

We care for our customers and that’s why we can totally understand your problem. That’s the reason why we have listed out some major symptoms behind the flashing up of OBD Code P209A. They are mentioned here as follows:

Common Symptoms

  • Check engine light can start flashing up
  • Affected fuel economy
  • Reduced Engine performance
  • Sometimes there might be no visible symptoms present
  • Black smoke might start emitting from the tailpipe during acceleration

How To Correct Reductant Injection Air Pressure Sensor B Circuit

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P209A:

  • Repair or replace the loose, broken or corroded wiring
  • Rehabilitate the defaults in the reduction injection pressure sensor circuit
  • You must fix the defective or corroded connectors
  • Make sure to mend the faulty exhaust system parts
  • Carefully adjust the faults in the exhaust gas temperature sensor (EGTS)
  • Recondition the non-functioning terminals

There is no need to get strained if your OBD Code is still flashing up as we are here at your service. Have a look at our superior variety of Reductant Injection Air Pressure Sensor, SCR controller, Powertrain Control Module (PCM) and many more. Now all your problems would vanish within no time.

Easy Diagnosis Of Engine Error OBD Code P209A

Do you wish to diagnose P209A error code easily? Here are some steps which you should follow in order to diagnose this fault code:

  • Initial step is to visually examine the wiring for faults, frays, or wires that have melted.
  • Visually inspect the connector for damage, frays, or corrosion.
  • Make sure to mend the defective wiring or connectors as per the requirement.
  • The mechanic should retest the system to make sure that the wiring and connectors are in good working condition.
  • The mechanic or the technician will use a diagnostic scanner or code reader like DVOM to visually scan for the error codes in the vehicle.
  • After performing a careful inspection, every of the stored codes and freeze frame data are retrieved as it can help down the way for further diagnosis process.
  • He will know that an intermittent condition persist, if the code does not return instantly.
  • Intermittent conditions are very tough to diagnose, and they need time to get worse before they can be diagnosed correctly.
  • Check the circuitry of the exhaust gas temperature sensor EGTS)/exhaust gas pressure sensor (EGPS) near where the hot exhaust constituents are close to wiring and connectors.
  • Rehabilitate the defaults in the circuitry. The entire system should be retested to make sure that the circuitry of the exhaust gas temperature sensor and pressure sensor are in good working condition.
  • After that it is essential to examine the resistance of the EGTS/EGPS. The specifications of the resistance are decided by the manufacturer, but are typically 150 ohms. A resistance reading of below 50 ohms would indicate that there is need to replace the defective sensor.
  • A heating component should be used to examine the resistance with the volt/ohmmeter. The level of the resistance would decline when the heating component is added and would rise when the sensor would cool.
  • If this would not happen, then it would indicate that there is a need to restore the faulty EGTS/ EGPS.
  • The voltage of the EGTS /EGPS, at the electrical connector should be checked properly. Keep in mind that the reading of the voltage should be at 5-volts.
  • Now if the voltage reading of the EGTS/EGPS would not be at 5-volts, then you should inspect the continuity between the PCM and the signal wire.
  • There would be a need to replace or reprogram the PCM if there is continuity.
  • There might be some flaws in the reductant injection air controller if no voltage is present on the sensor connector.
  • If the mechanic finds out that there is no voltage present in the sensor connector, then it would that there are some quirks in it. Reprogram the defective reductant injection air controller.
  • The P209A trouble code would start appearing due to less exhaust system back pressure, which is caused by a high performance aftermarket exhaust system. An in line resistor should be utilized to solve this issue.

Common Mistakes When Diagnosing The P209A Code

  • Sometimes the mechanic might not know the difference between the oxygen sensor for the reductant injection pressure sensor as both of them look same and he might replace the wrong sensor, giving rise to more problems.
  • Most mechanics simply neglect to examine the wiring, connectors and terminals for damage.

Other Diagnostic Codes Related To OBD Code P209A

P209B - Reductant Injection Air Pressure Sensor "B" Circuit Range/Performance

P209C - Reductant Injection Air Pressure Sensor "B" Circuit Low

P209D - Reductant Injection Air Pressure Sensor "B" Circuit High

P209E - Reductant Injection Air Pressure Sensor "A"/"B" Correlation