P245E Particulate Filter B Pressure Sensor Circuit
Content
P245E Particulate Filter B Pressure Sensor Circuit
OBD-II DTC Datasheet
Diesel Particulate Filter B Pressure Sensor Circuit
What does this mean?
This Diagnostic Trouble Code (DTC) is a generic transmission code, which means it applies to all vehicles since 1996 (Ford, Dodge, GMC, Chevrolet, Mercedes, VW, etc.). Although general in nature, the specific repair steps may differ depending on the brand / model.
If your vehicle displays an engine soon service indicator code P245E, the powertrain control module (PCM) has detected a malfunction in the electrical circuit of the DPF pressure sensor, which is designated B. Obviously, this code should only be presented in vehicles with diesel engine.
DPF is designed to remove ninety percent of carbon (soot) particles from diesel exhaust gases. Soot is most commonly associated with black smoke that rises from the exhaust fumes when the diesel engine is under strong acceleration. The DPF is housed in a steel built-in exhaust casing that resembles a muffler or catalytic converter. It is located upstream of the catalytic converter and / or NOx trap. While large particles of soot are trapped in the DPF element, small particles and other compounds (exhaust gases) can pass through it. DPF uses a wide variety of elemental compounds to trap soot and pass engine exhaust gases. These 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 filters. It is relatively inexpensive and has excellent filtration characteristics. Unfortunately, cordierite has problems melting at high temperatures, making it prone to failure when used in passive particulate filter systems.
The heart of any particulate filter is the filter element. When engine exhaust passes through the element, large soot particles are trapped between the fibers. As soot builds up, exhaust gas pressure increases accordingly. Once enough soot has accumulated (and the exhaust pressure has reached the programmed degree), the filter element must be regenerated to allow the exhaust gases to continue to pass through the DPF.
Active DPF systems regenerate automatically. In other words, the PCM is programmed to inject chemicals (including but not limited to diesel and exhaust fluid) into the exhaust gases at programmed intervals. This action causes the temperature of the exhaust gases to rise and the trapped soot particles are burned; releasing them in the form of nitrogen and oxygen ions.
A similar process is used in passive DPF systems, but requires the involvement of the owner and (in some cases) a qualified repairer. After the start of the regeneration procedure, it may take several hours. Other passive regeneration systems require the DPF to be removed from the vehicle and serviced by a specialized machine that completes the process and properly removes soot particles. When the soot particles have been removed sufficiently, the DPF is considered regenerated and the exhaust pressure must respond accordingly.
In most cases, the DPF pressure sensor is installed in the engine compartment, away from the DPF. It monitors the back pressure of the exhaust gases before they enter the particulate filter. This is achieved with (one or more) silicone hoses that are connected to the DPF (near the inlet) and the DPF pressure sensor.
When the PCM detects an exhaust pressure condition that is not within manufacturer's specifications, or the electrical input from the DPF B pressure sensor exceeds the programmed limits, a P245E code will be stored and the service engine lamp will shortly illuminate.
Symptoms and severity
Conditions for which this code is stored may result in internal engine or fuel system damage and should be repaired immediately. Symptoms of a P245E code may include:
- Excessive black smoke from the exhaust pipe
- Reduced engine performance
- Increased engine temperature
- Higher transmission temperatures
reasons
Possible reasons for setting this code:
- The diesel engine exhaust fluid reservoir is empty.
- Incorrect Diesel Exhaust Fluid
- Defective DPF pressure sensor
- DPF pressure sensor tubes / hoses clogged
- Open or short circuit in DPF pressure sensor B circuit
- Ineffective DPF Regeneration
- Inoperative DPF active regeneration system
Diagnostic and repair procedures
A good starting point is always to check the Technical Service Bulletins (TSB) for your particular vehicle. Your problem may be a known issue with a known manufacturer-released fix and could save you time and money while troubleshooting.
To diagnose the P245E code, you will need a diagnostic scanner, digital volt / ohmmeter, and a service manual from the manufacturer. An infrared thermometer can also come in handy.
I usually start my diagnosis by visually inspecting the associated harnesses and connectors. I would pay special attention to the wiring that is routed next to hot exhaust components and sharp edges. Check the battery and battery terminals at this time and check the generator output.
Then I connected the scanner and got all the stored codes and freeze frame data. I would write this down for future use. This can come in handy if this code turns out to be intermittent. Now clear the codes and test drive the vehicle.
If the code resets immediately, check that diesel engine exhaust fluid (if applicable) is present and of the correct type. The most common reason this code is stored is a lack of diesel engine exhaust fluid. Without the proper type of diesel engine exhaust fluid, the DPF will not be efficiently regenerated, leading to a potential increase in exhaust pressure.
Refer to the manufacturer's service manual for instructions on how to test a DPF pressure sensor using the DVOM. If the sensor does not meet the manufacturer's resistance requirements, it must be replaced. If sensor ok, check DPF pressure sensor supply hoses for blockages and / or breaks. Clean or replace hoses if necessary. High temperature silicone hoses must be used.
If the sensor is good and the power lines are good, begin testing the system circuits. Disconnect all associated control modules before testing resistance and / or continuity with the DVOM. Repair or replace open or shorted circuits as necessary.
Additional diagnostic notes:
- If the DPF pressure sensor hoses are melted or cracked, it may be necessary to re-route after replacement.
- Consult the owner / service manual to find out if your vehicle is equipped with an active DPF regeneration system or a passive system.
- Clogged sensor ports and clogged sensor tubes are common
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