Technical Description of OBD-II Trouble Code
Bank 2 Catalyst System 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 P200F, it means that the powertrain control module (PCM) has detected an excessive degree of catalyst system temperature for engine bank two. Bank 2 refers to the bank of the engine that does not contain the number one cylinder.
The catalyst system in a modern clean-burning diesel-powered vehicle is designed to reduce harmful exhaust emissions before they are released into the atmosphere. The catalytic converter, which acts as a filter, traps harmful emissions within a platinum filtration element. The extreme temperatures generated inside the catalytic converter help burn these harmful emissions elements.
The catalyst system is responsible for reducing most of the other exhaust emissions, although certain applications may also have a NOx trap. Exhaust gas recirculation (EGR) systems further reduce NOx emissions. However, larger and more powerful diesel engines require selective catalytic reduction (SCR) systems to meet strict federal emission standards in the US.
SCR systems inject diesel exhaust fluid (DEF) into the exhaust in front of the diesel particulate filter and/or the catalytic converter. This injection elevates the temperature of the filtration element, allowing it to perform more efficiently and release fewer harmful exhaust emissions into the atmosphere.
Exhaust temperature sensors are placed before and after the catalyst to monitor its temperature and efficiency. The entire SCR system is monitored and controlled by either the PCM or a stand-alone controller. The controller monitors various sensors to determine the appropriate time for DEF injection, which is necessary to maintain exhaust temperature within acceptable parameters and optimize pollutant filtration.
If the PCM detects excessive catalyst system temperature for engine bank two, a code P200F will be stored and a malfunction indicator lamp may illuminate.
A cutaway of a typical diesel particulate filter:
What is the severity of this DTC?
Any stored catalyst system codes may indicate a clogged exhaust system. The stored code P200F should be considered severe and addressed as quickly as possible to prevent catalyst damage.
What are some of the symptoms of the code?
Symptoms of a P200F trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P200F troubleshooting steps?
If SCR codes are also stored, address those first before attempting to diagnose the stored P200F code. Repair any pre-catalyst exhaust leaks before diagnosing this type of code.
To diagnose a code P200F, 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 intermittent code may be more difficult at this time. The conditions that contributed to the code being stored may need to worsen before an accurate diagnosis can be made.
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-catalyst 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 catalyst element or a failed SCR system.
