DPF sensors, like all sensors, can fail. What are DPF sensors? A Diesel Particulate filter is also known as a DPF and is used in a diesel engine to reduce soot.
This filter is essential for the environment, reducing the amount of smoke from the car’s exhaust.
What is a DPF Sensor?
The DPF sensor measures the amount of soot emitted by your exhaust system by measuring the pressure differential in the exhaust gas before and after the DPF. They take pressure readings before and after the DPF to determine the difference.
These sensors can compare the pressure to the external atmospheric pressure. These sensors also use the filter housing to create an RF resonance cavity. These sensors can measure the level of filter soot or ash in real-time.
DPF Sensors measure these parameters:
- Filter soot levels
- Filter ash levels
- Material spatial distribution
Why Do You Need A DPF Sensor?
DPF sensors are critical. These sensors allow for feedback control or optimization, a process in which you can optimize regeneration. This process allows for cost savings and longer component life.
DPF sensors generally serve two functions.
- To calculate the amount of soot accumulated in diesel particulate filters.
- To detect DPF failure.
How do I locate the DPF Sensor location?
Where is the DPF pressure sensor located? The DPF sensor is easy to find, and you can use one of these methods:
1. Follow the Pressure Lines
The pressure lines are a quick and straightforward way to locate the sensor. These will direct you to the sensor. You will find the sensor at the end of the pressure lines on most GL cars.
- If you cannot locate the sensor, follow these steps by following the pressure lines
- You can get your regular car tools (clamp tool, sockets, etc.)
- Use the sway bar to your advantage
iii. Remove the passenger-side air filter housing. You should now *see the sensor.
- Clear CLEL depending on the error code
DPF Sensor Error Codes
These codes will allow you to determine the status of your sensor.
- P2452 – Pressure sensor malfunction
- P2454 – sensor voltage too low
- P2455 – sensor malfunction
DPF-Related Fault Codes
- P1471 Diesel particulate filter (bank 1) regeneration not completed.
- P2003 Diesel particulate filter (bank 1) particulate mass too high.
- P242F Diesel particulate filter (bank 1) regeneration is not active.
- P244A Particulate filter differential pressure too low.
- P224B Particulate filter differential pressure too high.
- P2458 Particulate filter regeneration maximum regeneration.
- P2459 Particulate filter regeneration, regeneration frequency implausible.
- P246C High pressures at the inlet indicate a restriction of the DPF.
- P2463 can be described as “diesel particle filter restriction” and is a general code.
They also have a single plug and one or two 10mm bolts or clamps to hold it in place.
How to Clean Your DPF Sensor
Once you have identified the sensor, you can locate the problem. You can now specify the problem by looking at the codes.
In some cases, however, the sensor may need to be cleaned. These sensors can become ‘dirty’ from carbon deposits. Carbon cleaning or decarbonizing is required to fix this problem.
You can decarbonize the engine to remove carbon, an excellent method to repair your machine rather than replace them. Many companies offer carbon cleaning services.
Different types of DPF Sensors
Although they all detect DPF soot, different DPF sensors have other functions such as DPF soot load estimation and monitoring DPF failure.
These sensors can be classified into different types depending on the technology used to create them.
Differential Pressure: Use the filter pressure drop to estimate soot.
Radiofrequency Uses microwaves for soot building up.
Accumulating electrode: Measures the change in electrical properties of an electrode caused by a time-dependent soot deposit.
What is the Working Principle of a DPF Differential Pressure Sensing Device?
The DPF differential pressure sensor is typically mounted in an engine compartment to protect the sensor from heat. The electrical connector connects the sensor to the ECU and the DPF via two silicon pipes. The one connected before the DPF (upstream), and the other connects downstream of the filter (downstream). The sensor measures and compares the pressure difference between the exhaust gases before and afterward the filter, allowing the sensor to estimate how much DPM is trapped within the filter.
Why are DPF Differential Pressure Sensors Failing?
Like any other electrical sensor in an engine’s engine, the wires to ECU can be damaged by harsh vibrations and crack or melt from extreme heat. The sensor hoses can become clogged by soot from the exhaust, just as the DPF. If diesel particulate matter blocks the airways to the sensor, it can cause catastrophic damage to the DPF and, eventually, the engine.
What to Look For in a DPF Differential Pressure Sensor That is Failing
The DPF differential pressure sensor can stop signaling to the PCM for regeneration. If this happens, the DPF can become contaminated and eventually fail. These are signs that the DPF sensor is dying, and the DPF may not correctly regenerate.
- Poor engine performance
- Poor fuel economy
- High engine temperatures
- Transmission temperatures high
- Darker exhaust smoke (soot) is more noticeable.
- Check engine light
DPF failure can cause exhaust gases not to be purged entirely. Backpressure pushes exhaust back inside the combustion chamber, causing DPM (or soot) to mix with engine oil. The mixture of soot and oil will prematurely wear the engine bearings. It will only burn a portion of the fuel that should be exiting through the exhaust during regeneration. The residual energy can wash away any protective oil film from the internal engine components, causing catastrophic failure.
The DPF pressure sensor is essential for its longevity, and if it becomes obstructed, you cannot fix the regeneration process. The DPF pressure sensor will be removed and professionally cleaned or replaced. Both options can cost thousands of dollars. It will cost much more to replace a defective sensor and diagnose it before it is too late.
How to troubleshoot DPF Differential Pressure Sensors
First, it is good to check for visible damage when troubleshooting engine sensor problems. Start with the electrical connector for the sensor and check for cracking or melting. Replace all damaged wires.
Next, examine the hoses that are connected to the sensor. Next, inspect the hoses connected to the sensor for cracking or melting. If the hoses become damaged, they should be replaced or rerouted to prevent further damage. Check for any blockages or clogs if the hoses appear to be in good condition. If the hoses become clogged, they will need to be removed or replaced.
If all items pass physical inspection, the DPF differential pressure sensors can be tested using a multimeter set at 20V and a pressure gauge.
Turn the engine off and switch on the battery. Connect the multimeter ground to a negative terminal of the battery. Run a quick test to check the voltage. It should be approximately 12.6 volts.
Refer to the manufacturer’s manual for details on the signal, ground, and 5-volt reference, as well as back-probe the wires.
Without starting the engine, turn the ignition switch on. Ensure the voltage readings on the multimeter ranges from 4.5 – 5 volts on the volt reference and between 0.5 to 4.5 volts on the signal wire. For exact specifications on your vehicle, consult the OEM factory service information.
Start The Engine Using The Signal Wire Back Probed
Suppose there is any voltage change, rev the engine. You can test the connection hoses using a pressure gauge if there is no change.
While the engine is still running, disconnect the sensor’s hoses.
Use a pressure gauge to measure the pressure on both hoses. An exhaust backpressure gauge measuring 0-15 PSI will give you sufficient accuracy.
Recheck the signal voltage. The voltage should be equal to the pressures of the hoses. If the pressure values of the hoses are different, such as half PSI for the rear and one PSI for the front, then the voltage reading on the signal wire should be somewhere between 8 and 0.8 volts. If the voltage readings are off or the pressure values don’t match, the DPF differential voltage sensor will need to be replaced.
How to replace a defective DPF Differential Pressure Sensor
For specific instructions on how to replace a DPF differential pressure sensor that is faulty, refer to the manufacturer’s manual. To ensure you have enough space under your vehicle, attach the back wheel to the frame and use jack stands.
- You can find the DPF differential pressure sensor in the rear of the engine compartment.
- Take out any bolts or screws (sometimes Torx bolts) that hold the sensor in place.
- Gently move the sensor to loosen the screws that hold the hoses in place.
- Before you disconnect the sensor, make sure to note which side is connected to which hose.
- Compare the old and new sensors.
- Connect hoses in the same position as the new sensor and fasten them by tightening the clamps.
- Replace any bolts or screws that held the sensor in place.
- Connect the electrical connector to your new sensor.
- Double-check every connection to ensure everything is secure