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P200D Diesel Particulate Filter Over Temperature Bank 2

OBD-II Trouble Code Technical Description

Article by
Stephen Darby
Stephen Darby
ASE Certified Technician

Diesel Particulate Filter Over Temperature Bank 2

What does that mean?

This diagnostic trouble code (DTC) is a generic powertrain code and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Ford, Hino, Mercedes Benz, VW, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.


 

总裁俱乐部appIf your diesel powered, OBD-II equipped vehicle has stored a code P200D, it means that the powertrain control module (PCM) has detected an excessive degree of diesel particulate filter temperature for engine bank two. Bank 2 is the bank of the engine that doesn't contain the number one cylinder.

The diesel particulate filter, as it pertains to a modern clean burning diesel powered vehicle, is designed to reduce harmful exhaust emissions before they can be released into the atmosphere. Exhaust emissions consist mainly of hydrocarbons (HC), carbon monoxide (CO), nitrogen oxide (NOx), and particulate matter (soot - in diesel applications). The diesel particulate filter is basically a large (fine mesh) filter that is capable of withstanding extreme temperature. Engine exhaust flows through and harmful emissions are trapped within a platinum filtration element. The extreme temperatures generated inside the diesel particulate filter help to burn harmful emissions elements.

The primary responsibility of the diesel particulate filter is the reduction of soot from diesel engine exhaust. If you have noticed that modern diesel engines run cleaner and with less black smoke than diesels from a few decades ago; it is due to the implementation of the diesel particulate filter in the exhaust system.

Exhaust gas recirculation (EGR) systems go another step further in the reduction of NOx. Nevertheless, today’s larger and more powerful diesel engines cannot meet strict federal (U.S.) emission standards with the EGR, diesel particulate filter, and NOx trap alone. It was for this reason that selective catalytic reduction (SCR) systems were invented.

总裁俱乐部appSCR systems inject diesel exhaust fluid (DEF) into the exhaust in front of the diesel particulate filter and/or the catalytic converter. The precisely timed DEF injection elevates the temperature of the filtration element and allows it to perform more efficiently. It makes the filtration element last longer and allows fewer harmful exhaust emissions to be released into the atmosphere.

Exhaust temperature sensors are placed before and after the diesel particulate filter to monitor its temperature and efficiency. The entire SCS system is monitored and controlled by either the PCM or a stand-alone controller (which interacts with the PCM). Either way, the controller monitors the O2, NOx, and exhaust temperature sensors (as well as other inputs) to determine the appropriate time for DEF injection. Precise DEF injection is necessary to maintain exhaust temperature within acceptable parameters and optimize pollutant filtration.

总裁俱乐部appIf the PCM detects excessive diesel particulate filter temperature (for engine bank two), a code P200D will be stored and a malfunction indicator lamp may be illuminated.

A cutaway of a typical diesel particulate filter:
P200D Typical Diesel Particulate Filter

What is the severity of this DTC?

总裁俱乐部appAny stored diesel particulate filter codes may be precursor to a clogged exhaust system. The stored code P200D should be considered severe and addressed as quickly as possible. Catalyst damage could result if the conditions which contributed to the code being stored are not rectified in a timely manner.

What are some of the symptoms of the code?

总裁俱乐部appSymptoms of a P200D trouble code may include:

What are some of the common causes of the code?

Causes for this code may include:

What are some P200D troubleshooting steps?

If SCR codes are also stored, these should be addressed before attempting to diagnose the stored P200D. Pre-catalyst exhaust leaks should be repaired before attempting a diagnosis for this type of code.

You will need access to a diagnostic scanner, a digital volt/ohmmeter (DVOM), an infrared thermometer with a laser pointer, and a source of vehicle specific diagnostic information to diagnose a code P200D.

总裁俱乐部appIf you can find a technical service bulletin (TSB) that matches the vehicle year, make, and model; as well as the engine size, code/s stored, and symptoms exhibited, it could yield helpful diagnostic information.

总裁俱乐部appYou will want to begin your diagnosis with a visual inspection of the SCR injection system, exhaust temperature sensors, NOx sensors, and oxygen (02) sensor harnesses and connectors. Burnt or damaged wiring and or connectors should be repaired or replaced before proceeding.

Proceed by hooking the scanner to the vehicle diagnostic connector and retrieving all stored codes and pertinent freeze frame data. Write this information down before clearing the codes and test driving the vehicle until the PCM either enters readiness mode or the code is reset.

总裁俱乐部appThe code is intermittent and may be much more difficult to diagnose (at this time), if the PCM enters readiness mode. If this is the case, the conditions which contributed to the code being stored may need to worsen before an accurate diagnosis can be made.

总裁俱乐部appShould the code be reset, search your source of vehicle information to obtain diagnostic flow charts, connector pin out charts, connector face views, as well as component testing procedures and specifications. This information will be required to complete the next step of your diagnosis.

总裁俱乐部appUse the infrared thermometer to glean actual pre and post diesel particulate filter temperatures. Observe the scanner data stream to compare your actual findings with the information found on the scanner data display screen. Also compare exhaust temperature sensor data between engine banks. If exhaust temperature inconsistencies are detected, test the respective sensor/s using the DVOM. Sensors which do not comply with manufacturer specifications, should be considered defective.

总裁俱乐部appIf all sensors and circuitry appear to be functioning as intended, suspect that the diesel particulate filter is faulty or that the SCR system has failed.

Related DTC Discussions

Need more help with a P200D code?

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NOTE: This information is presented for information purposes only. It is not intended as repair advice and we are not responsible for any actions you take on any vehicle. All information on this site is copyright protected.

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