DPF pressure sensor: what it does, location, and faults
What does a DPF pressure sensor do?
The primary purpose of the diesel particulate filter pressure sensor or exhaust pressure sensor is to monitor how much soot there is in the diesel particulate filter (DPF) and how well the filter performs. It does this by measuring the exhaust back pressure upstream and downstream of the DPF. By calculating the difference between the two pressures, the device helps to determine how much contaminants have accumulated and sends a signal to the engine control unit to trigger the regeneration process when the filter becomes too saturated. A high pressure indicates that there is a higher amount of soot blocking the exhaust flows whereas low pressure indicates a lower soot content.
The DPF plays a critical role in reducing harmful emissions from diesel engines. To prevent it from becoming blocked, it undergoes what is known as active regeneration, which is basically when the control unit injects extra fuel or chemicals to increase the temperature of the exhaust and burn off the soot deposits. Without a functioning pressure sensor, the unit may not be able to trigger this process on time or may trigger it at random due to inaccurate signals. This can cause damage to the motor in the long term, and the cost to replace a clogged filter is high.
Find out more about the DPF filter cost here.
DPF pressure sensor location
The location of the component will depend on the specific vehicle model. If you need to inspect or replace the part, it is best to consult the car owner’s manual first to find its exact location. Another way of finding the DPF pressure sensor is to follow the pressure lines that lead to it. It is normally bolted to the side of the engine or attached near the firewall at the back of the engine compartment.
Symptoms of a faulty DPF pressure sensor
As mentioned above, the main consequence of a bad exhaust pressure sensor is a clogged or failing diesel particulate filter. Common causes include blocked sensor tubes or hoses and damage due to high operating temperatures and engine vibration. Here are some of the main signs that the sensor is faulty and DPF is not regenerating properly.
Top DPF pressure sensor symptoms:
- Increased fuel consumption
- Excessively high engine & transmission temperatures
- An increase in black exhaust smoke
- Difficulty starting the engine
- Check engine light
When the sensor has failed, the DPF is expected to follow. If the exhaust gases are unable to pass through the filter, the back pressure will force the exhaust back into the engine, causing soot to mix with the engine oil for the car. This significantly increases the risk of thermal engine damage and premature wear.
Common fault codes:
It’s sometimes possible to identify the cause of the problem by scanning the car’s onboard computer for fault codes using a diagnostic scanner (such as an OBD2 scanner). The following fault codes may appear in the case of differential pressure malfunctions.
P2452 – Diesel Particulate Filter Pressure Sensor A Circuit (malfunction detected in the circuit)
P2453 – Diesel Particulate Filter Pressure Sensor A Circuit Range/Signal Performance (the voltage reading is outside of the normal range)
P2454 – Diesel Particulate Filter Pressure Sensor “A” Circuit Low (input signal is too low)
P2455 – Diesel Particulate Filter Pressure Sensor A Circuit High (input signal is too high)
How much does a sensor replacement cost?
Without factoring in labour costs, the part itself can cost as little as £17 when you shop online. Replacing the differential pressure sensor is normally fairly straightforward, but there are several factors that could affect the replacement cost including the vehicle make and model, the year of manufacture and the engine size. However, considering that a DPF replacement typically costs over £1000, it is definitely worth replacing the sensor in good time.
You can easily find a compatible sensor online by selecting your vehicle e.g. “Vauxhall Insignia” and choosing a DPF pressure sensor for Vauxhall Insignia using online catalogue.
Is it safe to drive with the DPF light on?
It technically wouldn’t be a safety hazard, however, ignoring the warning light could end up doing serious damage to your engine in the long term, affecting your vehicle’s performance. A professional mechanic may need to carry out “forced regeneration” to restore the DPF and a detailed diagnosis may be necessary.
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