Error Code P20A8: What It Means & What To Do?

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The trouble code P20A8 can be elucidated as Reductant Injection Air Pressure Control Valve Circuit Low. 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.

This error code would start appearing if the PCM has detected some fault in the reductant injection air pressure control valve circuit. The main role of the reductant injector is to lower the noxious gases which are being expelled via the diesel particulate filter (diesel engines) or catalytic converter.

What causes this problem with the Reductant Injection Air Pressure Control Valve Circuit Low?

• Some issues related to the reductant injection air pressure control valve
• Unlocked reductant injection air pressure control valve harness
• Unsatisfactory electrical connection in the reductant injection air pressure control valve circuit

1. 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.
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 stores wrong OBD codes and can lead to misdiagnosis. 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 underperformance. Thus, replace faulty ECU now!
7. Diagnostic Tool - Choose from our diagnostic tools collection that will come handy to detect and correct the OBD error code.

You might be thinking that how would you diagnose these problems? We at Parts Avatar Canada would help you diagnose the major symptoms easily.

Common Symptoms

• The service engine soon light can start lighting up
• DPF regeneration might fail

The repairs which you will have to do to correct this fault code are simply straightforward; you can surely pinpoint the necessary repairs on the basis of your diagnosis. Have a look at some common fixes:

• It is essential to restore the flawed connector pins of shorted harness
• Repair or replace the quirky ECM
• The malfunctioning reductant injection air pressure control valve should be repaired or replaced as per the need
• Recondition the non-functioning reductant injection air pressure control valve harness
• Restore the reductant injection air pressure control valve circuit

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

• 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.
• Then the process of diagnosis should start. The mechanic should visually inspect the reductant heater system harnesses as well as connectors.
• Then the mechanic has to check the wires, connectors and other electrical components and quickly replace them if he finds them to be damaged or defective.
• After that all the stored codes as well as freeze frame data should be retrieved. This information should be written down before clearing the codes and then the vehicle should be take out for a test drive unless and until the powertrain control module would enter the readiness mode or the code is reset.
• Now if the PCM enters readiness mode, then it would that this code is intermittent and might be very difficult to diagnose it. If this is the real case, then you should allow the conditions which have given contribution in storing this code to worsen before the correct diagnosis can be made.
• Carefully reset the code and then the source of vehicle information to get diagnostic flow charts, connector pin out charts, connector face views, as well as component testing procedures and specifications should be searched. This information would be very helpful in completing the next step of your diagnosis.
• The DVOM should be used to check the power supply to the SCR control system. The fuses with the circuit loaded should be inspected so that the misdiagnosis can be avoided.
• Now if the right power (battery voltage) and ground circuits have been located, then a scanner should be used to activate the reductant injection air pressure control valve and check the output control circuit voltage.
• Then if the voltage is not sufficient, then it would that there are some faults in the controller or it might have faced a programming error.
• If the voltage output circuit is as per the parameters set by the manufacturer, then DVOM should be used to check the reductant injection air pressure control valve. If the valve is not as per the specifications set by the manufacturer, then it would mean that it has a failure. It is very important to replace it.
• Every time a repair work is carried out, make sure that the mechanic test drives the vehicle after every repair so that the diagnosis is successful. This can eventually help him to know as to where the error occurred.

Common Mistakes When Diagnosing The P20A8 Code

• There can be some faults in the powertrain control module
• Negligence in the reductant injection air pressure control valve
• Wiring problems