Guide To P20EF OBD Error Code Solutions

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SCR has been used for decades to reduce stationary source emissions. In addition, marine vessels worldwide have been equipped with SCR technology, including cargo vessels, ferries and tugboats. With its superior return in both economic and environmental benefits, SCR is also being recognized as the emissions control technology particularly helpful in meeting the U.S. EPA 2010 diesel engine emission standards for heavy-duty vehicles and the Tier 4 emissions standard for engines found in off-road equipment. SCR systems are also found in the growing number of diesel passenger vehicles.

OBD code P20EF means SCR NOx Pre- Catalyst Efficiency Below Threshold Bank 1 Issue.

SCR has been used for decades to reduce stationary source emissions. In addition, marine vessels worldwide have been equipped with SCR technology, including cargo vessels, ferries and tugboats. With its superior return in both economic and environmental benefits, SCR is also being recognized as the emissions control technology particularly helpful in meeting the U.S. EPA 2010 diesel engine emission standards for heavy-duty vehicles and the Tier 4 emissions standard for engines found in off-road equipment. SCR systems are also found in the growing number of diesel passenger vehicles.

When the SCR NOx Pre-Catalyst efficiency goes below the threshold capacity for the engine bank 1, OBD code P20EF gets stored in the Powertrain Control Module.

What causes this problem with the SCR NOx Pre- Catalyst Efficiency Below Threshold Bank 1?

• SCR NOx Sensor faulty
• Diesel Exhaust Fluid insufficient
• Faulty Selective Catalyst Reduction (SCR) Catalyst failure

1. Engine Control Module - Corrosion or damage due to moisture is one of the main reasons for ECM failure. Corrosion can enter the ECM through the wiring harness and moisture can enter by a failure in the seals in the ECM itself. Thus, replace it now!
2. Exhaust Gas Recirculation Valve - The main issue with the bad EGR valve is engine performance issues. A clogged or malfunctioning EGR valve can disrupt the vehicle’s air-fuel ratio, which can cause engine performance issues such as a reduction in power and fuel efficiency. The vehicle may also stall or hesitate while accelerating. Thus, replace it now!
3. Diesel Exhaust Fluid Pump - DEF is sprayed into the exhaust stream of diesel vehicles to break down dangerous NOx emissions into harmless nitrogen and water. This system is called Selective Catalytic Reduction (SCR) and can be found on 2010 and later model year trucks and many diesel pickups and SUVs. Thus, it plays a very vital role in controlling the emissions and if its pump is faulty, it must be replaced immediately.
4. Powertrain Control Module - An important reason of the failure in the PCM is the Injector wiring harness or the sensor wiring harness. Once again corrosion or breaks in the internal wiring in the harness can cause a short in the PCM or corrosion can enter the PCM through the wiring harness. Again, this is caused by exposure to the elements. Thus, replace and reprogramming might become necessary.
5. Automatic Transmission Module - Based on the information it receives from the engine, the module is the key to shifting the gears and changing the speeds. What it does is to convey the received signals to the clutch, which then execute the orders by making necessary changes to the fuel usage and power production. Thus, based on the failure, replace and reprogram as per necessity.
6. Fuel Injector - When the engine is under boost and at a higher rpm, it needs all the fuel the injectors can deliver. If the injectors are dirty and can’t keep up with the engine’s demands, the fuel mixture will lean out, causing detonation to occur. The leaning out may cause higher than normal exhaust temperatures and turbo failure. Thus, replace the damaged or clogged injector now!
7. Diagnostic Tool - One would require professional tools and equipment to diagnose any OBD code error. Buy new diagnostic tools and equipment from us!

Have you ever wondered why it is so important to know the symptoms of the problem? Well, it is extremely essential to know the symptoms of the problem in order to detect it. Keeping this in mind, let’s throw some light on few common symptoms of OBD error code P20EF.

Common Symptoms

• Check Engine Light illumination
• Affected fuel economy
• Increased levels of emissions

It is very important to fix the fault code P20EF. So here are some ways with which you can correct this issue:

• Replace EAS fuel injector
• Repair and reprogram the injector module
• Check and replace faulty exhaust system components
• Replace DEF pump
• SCR catalyst replacement

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 Selective catalytic reduction, Cumulative efficiency, ECM, SCR, DVOM, TSB, PCM, DEF and many more. Now all your problems would vanish within no time.

It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P20EF code to be stored:

• A qualified mechanic begins by using an OBD-II scan tool to read any codes present in the PCM.
• After the code is identified, freeze frame the data and cleared so that the car can be taken for test drive.
• Perform a road test of the vehicle with the similar conditions as that under the freeze frame data to see if the code reappears.
• Check for any open, short, corroded or damaged wirings and connections in association with the sensor and the circuit and repair or replace the faulty wirings immediately.
• If the Check Engine Light comes on, visually inspect the fuel tank, fuel lines, and fuel filter for any faults and damaged that can be repaired or replaced completely.
• Take the manual fuel pressure readings at the fuel rail and compare it to manufacturer’s specifications. Use a scan tool to compare manual readings to what the ECM sees.
• Lastly, the EAS fuel injector is tested and replaced if found faulty.
• Check for PCM (Powertrain Control Module) faults. Although rare in nature, these faults can cause wrong error being stored in the PCM and also hampers the vehicle’s performance by affecting the exhaust system, intake system, fuel delivery system, etc.

Common Mistakes When Diagnosing the P20EF 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.