P245E Diesel Particulate Filter Pressure Sensor “B” Circuit
OBD-II Trouble Code Technical Description
Diesel Particulate Filter Pressure Sensor B Circuit
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to all 1996-newer vehicles (Ford, Dodge, GMC, Chevrolet, Mercedes, VW, etc.). Although generic, the specific repair steps may vary depending on make/model.
If your vehicle is exhibiting a service engine soon indicator, accompanied by a code P245E, the powertrain control module (PCM) has detected a malfunction in the electrical circuit of the diesel particulate filter (DPF) pressure sensor that has been given the designation B. Obviously, this code should be presented only in vehicles that are powered by a diesel engine.
The DPF is designed to remove ninety-percent of carbon particles (soot) from diesel engine exhaust. Soot is most commonly associated with the black smoke that billows from the exhaust when a diesel engine is under heavy acceleration. The DPF is contained in a steel inline exhaust housing that resembles a muffler or catalytic converter. It is positioned ahead of the catalytic converter and/or the NOx trap. While large soot particles are trapped in the DPF element, small particles and other (exhaust gas) compounds are allowed to pass through. The DPF utilizes a wide variety of elemental compounds to trap soot and still allow engine exhaust to pass through. They include paper, metal fibers, ceramic fibers, silicone wall fibers, and cordierite wall fibers.
Cordierite is a type of ceramic based filtration and the most common type of fiber used in DPF applications. It is relatively inexpensive and possesses excellent filtration characteristics. Unfortunately Cordierite has issues with melting down at high temperatures, making it susceptible to malfunctions when used in passive DPF systems.
The heart of any DPF is the filtration element. As engine exhaust passes through the element, large particles of soot are trapped between the fibers. As soot is accumulated, exhaust pressure increases accordingly. After an adequate amount of soot is accumulated (and exhaust pressure has reached a programmed degree), the filtration element must be regenerated in order to allow spent exhaust gases to continue flowing through the DPF.
Active DPF systems are regenerated automatically. In other words, the PCM is programmed to inject chemicals (including but not limited to diesel fuel and diesel exhaust fluid) into the exhaust at programmed intervals. This action causes an increase in exhaust temperature and burns trapped soot particles; releasing them as ions of nitrogen and oxygen.
A similar process is used in passive DPF systems but requires input from the owner and (in some instances) a qualified repair facility. Once the regeneration procedure has been initiated, it may take hours to complete. Other passive regeneration systems require that the DPF be removed from the vehicle and serviced using a specialized machine that completes the process and disposes of soot particles appropriately. When soot particles are removed sufficiently, the DPF is considered regenerated and exhaust pressure should react accordingly.
In most cases, the DPF pressure sensor is mounted in the engine compartment, away from the DPF. It monitors exhaust back pressure before it enters the DPF. This is accomplished using (one or more) silicon hoses that are connected to the DPF (near the inlet) and the DPF pressure sensor.
When the PCM detects an exhaust pressure condition that doesn’t coincide with manufacturer’s specifications, or an electrical input signal from the DPF pressure sensor B that exceeds programmed limitations, a code P245E will be stored and a service engine soon lamp illuminated.
Symptoms & Severity
The conditions for causing this code to be stored could lead to internal engine or fuel system damage and should be addressed immediately. Symptoms of a P245E code may include:
Causes
Potential causes for this code to set are:
Diagnostic and Repair Procedures
A good starting point is always to check for technical service bulletins (TSB) for your particular vehicle. Your issue may be a known issue with a known fix put out by the manufacturer and can save you time and money during diagnosis.
A diagnostic scanner, a digital volt/ohmmeter, and a manufacturer’s service manual will be needed to diagnose a code P245E. An infrared thermometer may also be of use.
I typically begin my diagnosis with a visual inspection of related harnesses and connectors. I would pay particular attention to wiring that is routed near hot exhaust components and sharp edges. Test the battery and battery terminal ends at this time and check alternator output.
Next, I would connect the scanner and retrieve all stored codes and freeze frame data. I would write it down for future reference. It may come in handy if this code proves to be intermittent. Now, clear the codes and test drive the vehicle.
If the code immediately resets, check to make sure that diesel exhaust fluid is present (where applicable) and that it is of the correct type. The most common cause of this code being stored is a lack of diesel exhaust fluid. Without the proper type of diesel exhaust fluid, the DPF will not be regenerated effectively, causing a potential increase in exhaust pressure.
Consult the manufacturer’s service manual for instructions on how to test the DPF pressure sensor using the DVOM. If the sensor fails to comply with manufacturer’s resistance specifications, it must be replaced. If the sensor seems good, check for clogs and/or breakage in the DPF pressure sensor supply hoses. Clean or replace hoses as required. High temp silicon hoses must be used.
If the sensor is operational and supply lines are intact, begin testing system circuits. Disconnect all related control modules prior to testing resistance and/or continuity with the DVOM. Repair or replace open or shorted circuits as needed.
Additional diagnostic notes:
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"Delete Error Code Permanently, Disable DTC Error Code Function for p245e in the ECU"
In extreme cases, we even have the option to permanently remove the specific DTC p245e and disable the function of the specific error code in the ECU. All other fault code functions will then continue to work to protect the engine. This is different from clearing an error code with a diagnostic device. We have the option to permanently remove the function of the specific error code, so that it never comes back. Also emergency running that occurs on the specific error code can be solved in most cases.
Of course we prefer to first try to solve the cause of the error code, but sometimes the only solution is to permanently disable the DTC function of p245e.
