Technical Description of OBD-II Trouble Code
Bank 2 Diesel Particulate Filter Over Temperature
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to many OBD-II vehicles (1996-newer), including vehicles from Ford, Hino, Mercedes Benz, VW, etc. Although it is a generic code, the exact repair steps may vary depending on the year, make, model, and powertrain configuration of the vehicle.
If 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 refers to the bank of the engine that does not contain the number one cylinder.
The diesel particulate filter is a large filter designed to reduce harmful exhaust emissions before they are released into the atmosphere. It traps harmful emissions within a platinum filtration element and burns them at extreme temperatures generated inside the filter. This filter is responsible for reducing soot from diesel engine exhaust, resulting in cleaner and less smoky diesel engines compared to those from a few decades ago.
In addition to the diesel particulate filter, exhaust gas recirculation (EGR) systems and selective catalytic reduction (SCR) systems are used to further reduce emissions. SCR systems inject diesel exhaust fluid (DEF) into the exhaust to elevate the temperature of the filtration element and improve its efficiency. The entire SCR system is monitored and controlled by the PCM or a stand-alone controller.
If the PCM detects excessive diesel particulate filter temperature for engine bank two, a code P200D will be stored and a malfunction indicator lamp may illuminate.
A typical diesel particulate filter:
What is the severity of this DTC?
Any stored diesel particulate filter codes may indicate a clogged exhaust system. The stored code P200D should be considered severe and addressed promptly to prevent catalyst damage.
What are some of the symptoms of the code?
Symptoms of a P200D trouble code may include:
What are some of the common causes of the code?
Possible causes for this code include:
What are some P200D troubleshooting steps?
If SCR codes are also stored, address those first before diagnosing the stored P200D code. Repair any preexisting exhaust leaks before attempting to diagnose this code.
To diagnose a code P200D, you will need a diagnostic scanner, a digital volt/ohmmeter (DVOM), an infrared thermometer with a laser pointer, and vehicle-specific diagnostic information.
If available, consult a technical service bulletin (TSB) that matches the vehicle’s year, make, and model, as well as the engine size, stored code/s, and exhibited symptoms.
Begin the diagnosis with a visual inspection of the SCR injection system, exhaust temperature sensors, NOx sensors, and oxygen (O2) sensor harnesses and connectors. Repair or replace any burnt or damaged wiring or connectors before proceeding.
Connect the scanner to the vehicle diagnostic connector and retrieve all stored codes and freeze frame data. Write down this information before clearing the codes and test driving the vehicle until the PCM either enters readiness mode or the code is reset.
If the PCM enters readiness mode, diagnosing the code may be more difficult at this time, as the conditions contributing to the code being stored may need to worsen for an accurate diagnosis.
If the code is reset, refer to the vehicle information source for diagnostic flow charts, connector pinout charts, connector face views, component testing procedures, and specifications. This information is necessary to complete the next step of the diagnosis.
Use the infrared thermometer to measure actual pre and post diesel particulate filter temperatures. Compare your findings with the information displayed on the scanner data stream. Also compare exhaust temperature sensor data between engine banks. If there are inconsistencies, test the respective sensor/s using the DVOM. Sensors that do not comply with manufacturer specifications should be considered defective.
If all sensors and circuitry appear to be functioning properly, suspect a faulty diesel particulate filter or a failed SCR system.
