P20D4 - OBD Trouble Code

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Is your Car’s Check Engine Light illuminating on the dashboard? Do you find sudden decrease in the fuel economy? And is the car engine running rough with black smoke coming from tailpipe? This might be the indication of problems with the EAS fuel injector of the car which in other words can be an OBD P20D4 error.

P20D4 means Exhaust Aftertreatment Fuel Injector B Control Circuit High Issue.

If your diesel powered vehicle has stored a code P20D4, it means that the powertrain control module (PCM) has detected excess voltage in the control circuit for the exhaust aftertreatment fuel injector, designated B. The designation B indicates that multiple reductant injectors are in use.

What causes this problem with the Exhaust Aftertreatment Fuel Injector B Control Circuit High?

• Bad EAS fuel Injector
• Exhaust aftertreatment fuel injector circuit wiring and connector issue
• EAS fuel injector circuit problems
• SCR controller/PCM faults

1. Engine Control Module - ECM failures and faults can be very difficult to find and resolve as these are very rare and might require a complete reprogramming of the system to avoid wrong codes from getting stored in the system, leading to misdiagnosis. Replace it now!
2. Powertrain Control Module - Faulty PCM can disrupt the normal functioning of the vehicle by affecting the transmission system and the fuel delivery system. This will cause the system to store wrong OBD error and thus can lead to misdiagnosis.
3. Diagnostic Tools - Take help of a professional mechanic to diagnose OBD code error. Use high grade diagnostic tools to resolve this issue. Buy new tools and equipment from us!
4. Fuel Injector - Bad fuel injectors can cause starting issues, poor idles and affected performance. Thus, the replacements are in order. Buy new fuel injectors now!
5. Exhaust Gas Recirculation Valve - If the PCM detects any fault in the vehicle’s EGR valve circuit, it will set up the check engine light so that the driver is notified about the fault. Properly check for the EGR valve faults leading to this OBD code getting stored in the system. Get the faulty EGR valve replaced or else this fault code can turn up.
6. Diesel Exhaust Fluid Pump - Faulty DEF pump can lead to increased emission and affected vehicle performance. It can also hamper the fuel economy and the power output of the vehicle. Thus, replace faulty DEF pump now!

It is essential to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P20D4 here:

Common Symptoms

• Reduced/abnormal engine performance
• Affected fuel efficiency
• Lean exhaust codes
• Increased emissions from the tailpipe

Here are some ways with the help of which you will be able to correct the OBD Code P20D4.

• Bad EAS fuel injector replacement
• Diesel Exhaust Fluid Pump replacement
• EGR valve replacement
• Faulty wiring and connector repairs
• Powertrain Control Module repair and reprogramming

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It is essential to diagnose this fault code. Here are some steps which a mechanic should follow for diagnosing the problem that triggered a P20D4 code to be stored:

• Take the help of an experienced mechanic who will visually inspecting the exhaust system.
• Find and freeze frame data with the code. Then, clear the code and take the vehicle on a test drive under the same conditions.
• If the code reappears, perform a visual inspection of the components and its wiring.
• If the wiring is okay, the injector itself will be tested to confirm operation.
• The mechanic will repair or replace faults in relation to the reductant injection air pressure sensor, DEF pump and EGR valve. Also check for any wiring and harness issues and correct the damaged wirings.
• Check for the voltage output from the EAS fuel injector and if it isn’t under the desired range, suspect it to be fault and might need replacement.
• If there is no problem found, check for the faulty ECU. Although, this fault is very rare but can be a reason for problematic exhaust system, thus hampering the engine performance. The ECU needs to be replaced in such condition and has to be reprogrammed to erase any stored faulty error.

Common Mistakes When Diagnosing the P20D4 Code

• Powertrain Control Module (PCM) faulty
• Exhaust aftertreatment fuel injector issue
• Wiring and connector issue