P2458 Diesel Particulate Filter Regeneration Duration
OBD-II Trouble Code Technical Description
Diesel Particulate Filter Regeneration Duration
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.
When I encounter a stored code P2458, I know that the powertrain control module (PCM) has detected a malfunction in the diesel particulate filter (DPF) regeneration system. This particular code indicates that the regeneration process has not been completed properly. Obviously, use of this code is limited to diesel powered vehicles.
Designed to remove ninety-percent of carbon particles (soot) from diesel engine exhaust, DPF systems are critical in helping automakers meet today’s strict federal guidelines for clean burning diesel engines. Maybe you have noticed that modern diesel powered vehicles smoke far less than the diesel powered vehicles of yesteryear. Complex DPF systems are responsible for that.
Although there are several varying designs of DPF systems, most of them function in a similar manner. The DPF housing is a large steel muffler shaped device that contains a filtration element. Large soot particles are trapped by the filtration element and exhaust gases are allowed to flow through and exit the tailpipe. In some configurations, the DPF contains wall fibers that attract larger soot particles as they enter the housing. Other systems contain a loose web assembly that fills virtually the entire housing. The holes in the filtration device are sized so that larger soot particles are trapped and exhaust gases flow through.
In any case, when the filtration element has accumulated a certain degree of soot particles, it becomes partially clogged and exhaust back pressure increases. DPF back pressure is monitored by the PCM using a pressure sensor. Once back pressure reaches a particular level, the PCM takes measures to regenerate the filtration element.
In order for the filtration element to be regenerated, the temperature inside the DPF must reach approximately 1,200-degrees Fahrenheit. A specialized injection system is used to accomplish this in most instances. The electronically controlled injection procedure introduces a flammable chemical component, such as diesel fuel or diesel exhaust fluid, into the DPF. Once the specialized fluid has been introduced, the trapped soot particles are incinerated and released into the atmosphere (via the tailpipe) as harmless ions of nitrogen and water.
Active DPF regeneration systems are activated automatically by the PCM and the process takes place while the vehicle is being driven. Passive DPF regeneration systems require input from the operator (after the PCM has exhibited a cautionary warning) and usually takes place after the vehicle is parked. The regeneration procedure for passive systems may take hours to complete. I recommend that you check your vehicle owner’s manual to see with which type of DPF system your vehicle is equipped.
If the PCM detects that the regeneration process has not been completed as specified, or if exhaust pressure fails to reach the desired level, a P2458 could be stored and a malfunction indicator lamp may be illuminated.
Symptoms & Severity
Because DPF regeneration is crucial to maintaining desired exhaust back pressure, this code should be addressed with some degree of urgency. Symptoms of a P2458 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 scanner, a digital volt/ohmmeter, and a vehicle service manual (or the equivalent) are just a few of the tools that I would use to diagnose a P2458.
My normal diagnostic process is to inspect all system related wiring harnesses and connectors. I would vigilantly examine harnesses that are located near hot exhaust pipes and manifolds. My routine is to load test the battery, check battery terminal ends, battery cables, and alternator output at this time.
Next, I would connect the scanner to the diagnostic port and retrieve all stored trouble codes and freeze frame data. This information can be very helpful in testing, so I typically write it down prior to clearing the codes and test driving the vehicle.
If the code fails to reset immediately after test driving, test the level and quality of the diesel exhaust fluid and activate the DPF regeneration system. If the regeneration procedure was inadvertently interrupted, due to another unrelated problem that has been rectified, the regeneration process may be completed successfully after clearing the codes.
If the code immediately resets, use the DVOM and follow manufacturer’s recommendations for testing the DPF pressure sensor. If the sensor fails to comply with manufacturer’s resistance specifications, it must be replaced.
Additional diagnostic notes:
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"Delete Error Code Permanently, Disable DTC Error Code Function for p2458 in the ECU"
In extreme cases, we even have the option to permanently remove the specific DTC p2458 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 p2458.
