P20F4 - OBD Trouble Code

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The trouble code P20F4 can be defined as Reductant Consumption Too Low. It is the catalyst system which is responsible for reduction of all exhaust emissions although certain applications are also equipped with a NOx trap.

The reductant sensor is being monitored by the engine control module. This trouble code would be set by the ECM when the reductant sensor would not be as per the specifications set by the manufacturer. The engine control module, powertrain control module or the transmission control module monitors this circuit depending upon the particular automobile.

What causes this problem with the Reductant Consumption Too Low?

• Some flaws in the reductant
• Reductant harness might be opened or sometimes shorted
• Reductant circuit might have inadequate electrical connection

1. Engine Control Module - Dead cells in batteries can cause a failure in the engine control module. Many times a battery is left in the rig long after a cell has died. This would affect the grounding in the car battery.
2. Powertrain Control Module - If there are some faults in the PCM, then it may throw off the timing and fuel settings of the engine, which can negatively affect the performance. A flawed PCM may cause the vehicle to experience a reduction in fuel efficiency, power as well as acceleration.
3. Exhaust Gas Recirculation Valve – Bad EGR valve can cause many performance issues. Common signs include engine performance issues like decreased power and acceleration, rough idle, and the Check Engine Light coming on. Thus, replace faulty EGR valve now!
4. Diesel Exhaust Fluid Pump – If the DEF pump will not function properly, it can cause increased emissions in the exhaust system and reduced the longevity of the filtration elements in the exhaust system. Thus, replace faulty pump immediately.
5. Electronic Control Unit - Do you know that the poor performance or unexplained drops in fuel economy or efficiency are often associated to onboard car computer problems, or defective ECU issues?
6. Diagnostic Tools - 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!

Our main motive is to achieve customer satisfaction as for us our customers are everything and that’s why we will help you to diagnose P20F4 code by mentioning some major symptoms below:

Common Symptoms

• The service engine soon light can start lighting up

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 P20F4:

• You must fix the defective electronic control unit
• Make sure to mend the faulty reductant sensor circuit
• It is essential to restore the flawed reductant sensor
• Rehabilitate the defaults in the reductant sensor harness
• Carefully adjust the faults in the PCM

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Here are some steps which you should follow in order to diagnose this fault code:

• This is a general type of error code which is diagnosed with the help of a scanner.
• The current data along with freeze frame data are recorded, and the codes are then cleared to see if they reoccur.
• The vehicle is inspected for any problems with the wiring and connectors to check for loose connections, corrosion, or shorts.
• A scanner should be used to retrieve all stored codes and pertinent freeze frame data. It would be a great idea to write this information down before the codes have been cleared.
• Then the vehicle should be taken out for a test-drive until the PCM either enters readiness mode or the code is reset.
• Now if the PCM enters readiness mode at this time, the code is intermittent and it would be very difficult to diagnose.
• If this is the situation, the conditions which contributed to the code being stored may need to worsen before a correct diagnosis can be made.

• If the code is immediately reset, the other step of your diagnosis would need that you search your automobile information source for diagnostic flow-charts, connector pin-out charts, connector face views, as well as constituent testing procedures/specifications.
• The DVOM should be used to test the reductant pressure sensor according to manufacturer specifications.
• Components which do not test within maximum allowable parameters should be considered faulty.
• If actual reductant system pressure is as per the specifications, the code P20F4 would exist, and the sensor is in working order, use the DVOM to test input and output signal circuits between the pressure sensor and the PCM/SC.

Common Mistakes When Diagnosing The P20F4 Code

• Common mistakes while diagnosing this trouble code are unnecessary and expensive replacements which usually happen when one don’t follow all the steps carefully
• The most common mistake while diagnosing this code is missing out on diagnosing steps which further leads to the expensive and unnecessary replacements. It is always recommended to seek help of experienced diagnostician to avoid any mistakes.