Technical Description of OBD-II Trouble Code
Bank 1 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 P200E, it means that the powertrain control module (PCM) has detected an excessive degree of catalyst system temperature for engine bank one. Bank 1 refers to the bank of the engine that contains 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 is a large filter capable of withstanding extreme temperatures, traps harmful emissions within a platinum filtration element. The extreme temperatures inside the catalytic converter help burn these harmful emissions elements.
The catalyst system is responsible for reducing almost all other exhaust emissions, although some applications also have a NOx trap. Exhaust gas recirculation (EGR) systems further reduce NOx. However, larger and more powerful diesel engines today require selective catalytic reduction (SCR) systems to meet strict federal (U.S.) emission standards.
SCR systems inject diesel exhaust fluid (DEF) into the exhaust in front of the diesel particulate filter and/or the catalytic converter. The precise timing of DEF injection improves the efficiency of the filtration element, prolongs its lifespan, and reduces harmful exhaust emissions.
Exhaust temperature sensors monitor the temperature and efficiency of the catalyst. The entire SCR system is monitored and controlled by either the PCM or a stand-alone controller. The controller uses inputs from O2, NOx, and exhaust temperature sensors to determine the appropriate time for DEF injection. Precise DEF injection is necessary to maintain exhaust temperature within acceptable parameters and optimize pollutant filtration.
If the PCM detects excessive catalyst system temperature for engine bank one, it stores a code P200E and may illuminate the malfunction indicator lamp.
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 P200E should be considered severe and addressed as quickly as possible to prevent catalyst damage. Failure to rectify the conditions that led to the code being stored could result in catalyst damage.
What are some of the symptoms of the code?
Symptoms of a P200E trouble code may include:
What are some of the common causes of the code?
Possible causes for this code may include:
What are some P200E troubleshooting steps?
If SCR codes are also stored, address those first before attempting to diagnose the stored P200E code. Repair any pre-catalyst exhaust leaks before diagnosing this type of code.
To diagnose a code P200E, 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 year, make, and model, as well as the engine size, stored code/s, 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 relevant 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 since the conditions that led to the code being stored may need to worsen for an accurate diagnosis.
If the code is reset, refer to your source of vehicle information 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 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 catalyst element or a failed SCR system.
