Technical Description of OBD-II Trouble Code
The circuit range/performance of the Diesel Particulate Filter Pressure Sensor B
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that is applicable to all vehicles manufactured from 1996 onwards (Ford, Dodge, GMC, Chevrolet, Mercedes, VW, etc.). Although it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
When encountering code P245F, it means that the powertrain control module (PCM) has detected a malfunction in the electrical circuit of the diesel particulate filter (DPF) pressure sensor designated as B. This code will only appear in vehicles equipped with a diesel engine.
DPF systems in OBD-II vehicles are designed to remove ninety percent of carbon particles (soot) from the exhaust of diesel engines. The black smoke emitted from the exhaust of a diesel engine during heavy acceleration is caused by soot. The DPF is housed in a steel inline exhaust housing that resembles a muffler or catalytic converter. It is positioned before the catalytic converter and/or the NOx trap. The DPF element is responsible for trapping large soot particles, while allowing small particles and other exhaust gas compounds to flow through.
Various elemental compounds, such as paper fibers, metal fibers, ceramic fibers, silicone wall fibers, and cordierite wall fibers, are used by the DPF to trap large soot particles and allow engine exhaust to flow through. The most commonly used fiber in DPF applications is cordierite, which is ceramic-based and offers excellent filtration characteristics at an affordable cost. However, cordierite is prone to overheating at higher temperatures, which can lead to malfunctions in vehicles equipped with passive DPF systems.
The filtration element is the core component of any DPF. As engine exhaust flows through the element, large soot particles are trapped between the fibers, causing an increase in exhaust pressure. Once the exhaust pressure reaches a programmed level and a sufficient amount of soot is accumulated, the filtration element must undergo regeneration. This process allows spent exhaust gases to continue flowing through the DPF.
DPF systems with automatic regeneration are known as active DPF systems. In these systems, the PCM injects chemicals, including diesel fuel and diesel exhaust fluid, into the exhaust at programmed intervals. This injection increases the exhaust temperature and burns the trapped soot particles, releasing them as ions of nitrogen and oxygen.
Passive DPF systems follow a similar process but require input from the vehicle owner. In some cases, a qualified repair facility must handle the regeneration process, which can take several hours to complete. In certain situations, the DPF may need to be removed from the vehicle and serviced using a specialized machine that completes the regeneration process and disposes of the soot particles appropriately.
The DPF pressure sensor is typically mounted in the engine compartment, away from the DPF. It monitors exhaust back pressure as it enters the DPF. Silicon hoses are used to connect the DPF and the DPF pressure sensor for this purpose.
A code P245F is stored when the PCM detects an exhaust pressure condition that does not align with the manufacturer’s specifications or when the electrical input signal from DPF pressure sensor B exceeds programmed limitations.
Symptoms & Severity
This code should be treated as urgent as it indicates conditions that could potentially cause internal engine or fuel system damage. Symptoms of a P245F code may include:
Causes
Possible causes for this code to be triggered are:
Diagnostic and Repair Procedures
It is always advisable to check for technical service bulletins (TSB) specific to your vehicle as a starting point. Your issue may be a known problem with a known solution provided by the manufacturer, which can save time and money during diagnosis.
A manufacturer’s service manual, a diagnostic scanner, and a digital volt/ohmmeter are essential tools for diagnosing a code P245F. An infrared thermometer may also be useful.
The diagnosis should begin with a visual inspection of related harnesses and connectors, paying close attention to wiring that is near hot exhaust components or sharp edges. Test the alternator output, check the battery, and inspect the battery terminal ends at this stage.
Next, connect the scanner and retrieve all stored codes and freeze frame data. It is important to write down this information for future reference. Clear the codes and test drive the vehicle.
Ensure that diesel exhaust fluid is present (if applicable) and that it is the correct type, especially if the code immediately reappears. The lack of diesel exhaust fluid is a common cause of this code. The DPF cannot regenerate effectively without the proper type of diesel exhaust fluid, leading to increased exhaust pressure.
Using a digital volt/ohmmeter, test the DPF pressure sensor according to the manufacturer’s service manual instructions. If the sensor fails to meet the manufacturer’s resistance specifications, it must be replaced.
If the sensor checks out and there are no clogs or breakage in the DPF pressure sensor supply hoses, proceed to test the system circuits. Disconnect all related controllers before testing resistance and/or continuity with the digital volt/ohmmeter. Repair or replace any open or shorted circuits as necessary.
Additional diagnostic notes:
