The advent of the autonomous car has highlighted the fundamental importance of having good sensors. That being said, we have long been committed to providing effective – and reliable – sensors to our customers. So whether you are looking for engine and transmission sensors, or for comfort and safety – not to mention emissions and e-mobility – you should definitely take a look at our range.
Part of the anti-pollution system, this type of sensor has been compulsory since 2011, particularly on diesel engines, in order to comply with European regulations regarding polluting emissions (Euro 5 standard). Numerous pollutants are emitted during combustion in a diesel engine – some as gases and others as dust. These particles are stored in a compartment in the exhaust line called the particle filter. The filter accumulates pollutant emissions. It will then empty itself when full, in order to be able to store particles again. When that happens, it eliminates them by increasing its temperature in order to burn them. It can then start a new cycle.
In that regard, the role of the differential pressure sensor (or DPF sensor) is to evaluate the filling of this filter. Its function is to measure the pressure difference between the inlet and outlet of the particulate filter (or compared to atmospheric pressure).
There are different models of DPF sensors on the market: some have two connection tubes (which are then connected to the upstream and downstream part of the particulate filter) while others have only one tube. In the latter, the downstream value – similar to atmospheric pressure – is taken as the reference value.
PIEZORESISTIVE TECHNOLOGY
The sensor element is of the Piezoresistive type with a Wheatstone bridge configuration, which operates by means of a diaphragm that shifts under air pressure. This changes the resistance of the sensors, generating electrical signals. This information is then transmitted to the ECU, which interprets it to optimize the air/fuel mixture.
SYMPTOMS
The following symptoms are often associated with DPF sensor failure:
DIAGNOSIS PROCEDURE
First and foremost, you need to visually inspect the differential pressure sensor to determine the presence of a fault. It is therefore strongly recommended to check the following:
It is also possible to check the contact spacing with a male terminal (resistance to insertion). Using a voltmeter, check the 5V supply and the sensor ground. Also measure 5V on the signal wire with the sensor disconnected. By shunting the signal wire and the ground, the voltage drops to 0.
After disconnecting the particulate filter’s two pressure taps, measure the output signal with an oscilloscope and view the differential pressure value (0 hPa). Blow into the upstream pressure port: no change in voltage or differential pressure. After changing the differential pressure sensor, perform the test again. Measure the output signal at 0 hPa (higher signal). By blowing into the orifice, the signal and the differential pressure increase.
If the above tests are not conclusive, you must replace your DPF sensor.
CAUSES OF FAILURE
It is possible that a differential pressure sensor is no longer working due to:
INSTALLATION INSTRUCTIONS
To ensure a quick and efficient installation, you must refer to the following instructions:
INSTALLATION TIPS
As the differential pressure sensor is essential for the treatment of pollutant emissions, it is important to follow a certain number of recommendations when replacing it:
PREVENTIVE INFORMATION
The above items are provided for information purposes only. They do not replace the advice of a qualified technician or mechanic. We strongly recommend that you consult a professional if you are unsure of what to do. Otherwise, we cannot accept responsibility for any damage to your vehicle.
When a differential pressure sensor fails, the DPF light comes on or the glow plug light flashes. Your vehicle’s fuel consumption will increase, and the engine will lose power. Without the correct information, your particulate filter may start untimely regeneration cycles, which may lead to premature failure of other components in the exhaust system and/or engine. Conversely, there is a good chance that the particulate filter will not regenerate as often, which can lead to clogging.
First of all, you should visually check the differential pressure sensor; i.e., the sensor itself (presence of dirt), the connector (presence of oxidation) and its pipes (neither broken nor clogged).
It is also possible to check the contact spacing with a male terminal (resistance to insertion). Using a voltmeter, check the 5V supply and the sensor ground. Also measure 5V on the signal wire with the sensor disconnected. By shunting the signal wire and the ground, the voltage drops to 0.
After disconnecting the particulate filter’s two pressure taps, measure the output signal with an oscilloscope and view the differential pressure value (0 hPa). Blow into the upstream pressure port: no change in voltage or differential pressure. After changing the differential pressure sensor, perform the test again. Measure the output signal at 0 hPa (higher signal). By blowing into the orifice, the signal and the differential pressure increase.
If the above tests are not conclusive, you need to replace your vehicle’s differential pressure sensor.
Although automotive sensors meet very high standards, they are not eternal, and several elements may require replacement, including deteriorated hoses, cables and/or connectors, but also the sensor element, which may result in a poor pressure reading. Overly frequent regeneration of the particulate filter will reduce its durability. On the other hand, if regeneration is not frequent enough, the particles can become clogged and cause premature damage. If the connection between the pipes and the sensor is broken due to a cut, crack or obstruction, the sensor will no longer be able to perform its measurements.
We recommend the following steps to replace your differential pressure sensor as efficiently as possible and to limit possible mistakes:
As a sensor specialist, we recommend the following to extend your differential pressure sensor’s durability:
