Technical Description of OBD-II Trouble Code
Bank 1 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 P200C, it means that the powertrain control module (PCM) has detected an excessive degree of diesel particulate filter temperature for engine bank one. Bank 1 refers to the bank of the engine that contains the number one cylinder.
The diesel particulate filter is a large filter designed to reduce harmful exhaust emissions, such as hydrocarbons (HC), carbon monoxide (CO), nitrogen oxide (NOx), and particulate matter (soot), before they are released into the atmosphere. It can withstand extreme temperatures and uses a platinum filtration element to trap harmful emissions. The extreme temperatures inside the filter help burn these emissions.
The primary purpose of the diesel particulate filter is to reduce soot from diesel engine exhaust. The implementation of this filter in modern diesel engines has resulted in cleaner running engines with less black smoke compared to older diesel engines. However, larger and more powerful diesel engines require additional systems, such as exhaust gas recirculation (EGR) and selective catalytic reduction (SCR), to meet strict emission standards.
SCR systems inject diesel exhaust fluid (DEF) into the exhaust system to elevate the temperature of the filtration element and improve its efficiency. Exhaust temperature sensors monitor the temperature and efficiency of the diesel particulate filter. The entire SCR system is controlled by the PCM or a stand-alone controller, which monitors various sensors to determine the appropriate time for DEF injection. Precise DEF injection is necessary to maintain acceptable exhaust temperature and optimize pollutant filtration.
If the PCM detects excessive diesel particulate filter temperature for engine bank one, it will store a code P200C and may illuminate the malfunction indicator lamp.
A cutaway of 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 P200C should be considered severe and addressed promptly to prevent catalyst damage.
What are some of the symptoms of the code?
Symptoms of a P200C trouble code may include:
What are some of the common causes of the code?
Possible causes for this code include:
What are some P200C troubleshooting steps?
If there are also stored SCR codes, address those first before diagnosing the stored P200C code. Repair any preexisting exhaust leaks before attempting to diagnose this code.
To diagnose a code P200C, 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 codes, and exhibited symptoms. This information can provide helpful diagnostic guidance.
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 stored code 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 to complete the next step of the diagnosis.
Use the infrared thermometer to measure actual pre and post diesel particulate filter temperatures. Compare these readings with the information displayed on the scanner data stream. Also compare exhaust temperature sensor data between engine banks. If there are inconsistencies in exhaust temperature, 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 correctly, suspect a faulty diesel particulate filter or a failed SCR system.
