Technical Description of OBD-II Trouble Code
Circuit High for Diesel Particulate Filter Pressure Sensor A
What does that signify?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to all vehicles manufactured in 1996 or later (Ford, Dodge, GMC, Chevrolet, Mercedes, VW, etc.). While it is a generic code, the specific repair steps may vary depending on the make and model of the vehicle.
When code P2455 is stored, it means that the powertrain control module (PCM) has detected a high voltage input signal from the circuit of the diesel particulate filter (DPF) pressure sensor designated as A. This code is only used in vehicles equipped with diesel engines.
DPF systems are becoming increasingly common in diesel-powered vehicles. They are designed to remove ninety percent of carbon particles (soot) from the exhaust of diesel engines. Diesel engines are known for emitting black smoke from the exhaust, especially during heavy acceleration, and soot is the main component of this smoke. The DPF is housed in a steel container and typically resembles a muffler or catalytic converter. It is positioned before the catalytic converter and/or the NOx trap. The DPF element is designed to trap large soot particles while allowing smaller particles and other exhaust gas compounds to pass through. Various elemental compounds, such as paper fibers, metal fibers, ceramic fibers, silicone wall fibers, and cordierite wall fibers, are used to trap the larger soot particles. Ceramic-based cordierite is the most commonly used fiber in DPF applications due to its excellent filtration characteristics. However, cordierite can experience malfunctions in vehicles equipped with passive DPF systems when exposed to high temperatures.
The filtration element is the core component of the DPF. It is designed to trap large soot particles between the fibers while allowing engine exhaust to flow through. When a large amount of soot particles accumulates in the DPF, exhaust pressure increases. Once the exhaust pressure reaches a predetermined level, the filtration element must be regenerated. Regeneration of the DPF allows exhaust gases to continue flowing through the DPF and helps maintain the correct exhaust pressure level.
There are two types of DPF systems: active and passive. Active DPF systems are automatically regenerated and involve the PCM injecting chemicals, such as diesel fuel and diesel exhaust fluid, into the exhaust at programmed intervals. This injection increases exhaust temperature, causing trapped soot particles to burn and be released as ions of nitrogen and oxygen. Passive DPF systems require some form of input from the operator, and certain models may require a qualified repair facility for the regeneration process. DPF regeneration can take several hours to complete once initiated.
After the filtration element has been effectively regenerated, exhaust pressure should decrease to an acceptable level. The DPF pressure sensor is typically mounted remotely from the DPF itself. Silicon hoses are used to monitor exhaust back pressure as it enters the DPF and connects to the DPF pressure sensor.
A code P2455 will be stored if the PCM detects exhaust pressure that exceeds the manufacturer’s specifications or an electrical input signal from DPF pressure sensor A that exceeds programmed limitations.
Symptoms & Severity
Conditions that could lead to this code may also cause internal engine or fuel system damage and should be considered urgent. Symptoms of a P2455 code may include:
Causes
Possible causes for this code to be set are:
Diagnostic and Repair Procedures
It is always a good idea 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 you time and money during diagnosis.
To diagnose a code P2455, you will need a digital volt/ohmmeter, a manufacturer’s service manual, and a diagnostic scanner. I recommend beginning the diagnosis with a visual inspection of related harnesses and connectors. Check the wiring near hot exhaust components and sharp edges. Also, ensure that you check the alternator output, battery voltage, and battery terminal ends.
Next, connect the scanner and retrieve all stored codes and freeze frame data. Make sure to write down this information for future reference, and then clear all stored codes.
Use the DVOM to test the DPF pressure sensor according to the manufacturer’s recommendations. Consult the service manual for specific instructions. Any sensor that fails to meet the manufacturer’s resistance specifications must be replaced.
If the sensor checks out and the DPF pressure sensor supply hoses are clear, proceed to test the system circuits. To prevent damage to the PCM, disconnect all related controllers before testing resistance and/or continuity with the DVOM.
Additional diagnostic notes:
