DPF pressure sensor and pipes: symptoms, checks and fixes

What does a DPF pressure sensor do? It tells the engine computer how full the diesel particulate filter (DPF) is. Two small lines carry exhaust pressure from just before and just after the filter to the sensor, and the difference between the two rises as soot builds up^1,2. The engine computer uses that reading to decide when to burn the soot off, a process called regeneration^1,2. If a pipe or hose splits, blocks or comes off, the reading is wrong, and the vehicle can behave as if the DPF itself has failed: warning lights, regenerations that don’t happen, lost power^3,5. So check the pipes and hoses first, then the sensor, and the filter last^2,4.

The short answer

• Symptoms: the engine warning light, loss of power or limp mode, black smoke and poorer fuel economy^2,3,5.
• Usual causes: a split, cracked, melted or soot-blocked pipe or hose, an exhaust leak near the sensor’s pipes, a wiring or connector fault, or the sensor itself^2,3,6.
• Fault codes: P2452 to P2455 point at the sensor’s circuit; P244A and P244B mean the pressure across the filter looks too low or too high^2,3.
• Cost: our DPF pressure pipes cost €34.99 to €119.99, and a type-approved DPF on its own €154.99 to €547.99. Prices on 7 November 2026, in euro without VAT: Irish VAT and any customs duty are collected by the courier.
• The NCT: if the engine warning light stays on with the engine running, the smoke test isn’t carried out and the vehicle fails⁷.

Below: how the sensor and its pipes work, where to find them, the symptoms, what to check and in what order, the fault codes, the NCT, and how to choose the right pipe.

How the DPF pressure sensor works

A DPF fills with soot as it works. The fuller it gets, the harder the exhaust has to push through it, so the pressure in front of the filter rises compared with the pressure behind it. The differential pressure sensor measures that pressure drop across the filter, and the engine computer turns it into an estimate of how much soot the filter holds^1,2. Bosch, which makes these sensors, describes the reading as the basis for regenerating the filter on demand, only when it needs it, which saves fuel¹.

The sensor is connected to the exhaust by two lines: one tapped in before the filter and one after it². Depending on the vehicle, the lines are rubber or silicone hoses^2,3,4, or a rigid metal pipe from the filter joined by a short hose to the sensor. The DPF pressure pipes we sell are those metal sections: typically a bent metal tube that screws into the filter at one end, with a spigot for the hose at the other, and often a bracket to hold it in place.

Some vehicles also have a second differential pressure sensor elsewhere, for the exhaust gas recirculation (EGR) system¹, so make sure any reading or part is the DPF one.

Where is the DPF pressure sensor?

Usually in the engine compartment, not on the filter: it is mounted away from the exhaust to protect it from the heat^2,3, often at the back of the engine compartment². The quickest way to find it is to follow the two small lines from the DPF. They end at a small sensor with two pressure connections and an electrical connector^1,2. The exact place varies from vehicle to vehicle: the workshop data for your vehicle shows it.

Symptoms of a faulty DPF pressure sensor or pipe

A split, blocked or disconnected line gives the engine computer a reading that is too low, too high, frozen or missing altogether^3,5. What you notice depends on which:

• The engine warning light, with a stored fault code^3,6.
• Lost power, or limp mode. HELLA, the parts maker, describes how on the Dacia Dokker defective hoses or a faulty sensor can leave the engine computer with distorted or missing values. It then switches to emergency running to protect the engine, and the vehicle may only reach 80 to 100 km/h (about 50 to 60 mph)⁵. Mercedes-Benz lists reduced engine power and the engine warning lamp for differential pressure sensor faults on the Sprinter⁶.
• Black smoke, higher engine temperature and poorer fuel economy^2,3.
• A DPF that blocks. If the sensor stops calling for regeneration, the filter can block completely and fail². And when the pressure across the filter reads too low, the engine computer may decide the filter isn’t there at all, store P244A and switch active regeneration off³.

None of these is unique to the pressure sensor: a genuinely blocked filter shows most of them too. That is why the order of the checks matters.

Pipe, hose, sensor or filter: what to check first

BM Catalysts, the manufacturer of the DPFs we sell, says DPF fault codes are rarely caused by a defective filter. Its list of checks before a DPF is replaced starts with the pressure pipes and sensors: the pipes free from blockages, the sensors working correctly^3,4. In practice, the order is:

1. Look. With the engine cold, trace both lines from the filter to the sensor. Look for hoses that are cracked, split or melted, or have come off, and metal pipes that are cracked or rusted through. Check the sensor’s connector and wiring for damage too^2,5.
2. Clear or replace a blocked line. Soot from the exhaust can block the pipes and hoses, and a blocked line has to be cleared or replaced².
3. Look for exhaust leaks before or near the sensor’s pipes, which also upset the reading^2,3.
4. Read the sensor on a test drive. A garage watches the sensor’s live value with a diagnostic tool. If the value stays static or doesn’t follow the engine load, the sensor and its hoses come off for a closer look⁵.
5. Then the sensor. If the lines and wiring are sound and the reading still doesn’t make sense, the sensor itself is faulty². On the Sprinter’s V6 diesel, Mercedes-Benz found that a compound given off by the rubber hoses could settle on the sensor and damage it. Its fix was a new sensor and a full set of new hoses, with the instruction not to use hoses from old stock⁶.
6. Only then the filter. If everything above checks out and the codes still point at the filter, look at the DPF, and at why it blocked: see blocked DPF? The causes to fix before replacing it.

After the repair, the fault memory is cleared and the vehicle test-driven⁵. A new sensor’s offset has to be programmed into the engine computer², and if a new DPF is fitted, the engine computer must be reset and a forced regeneration run^3,4.

The fault codes, in brief

Code	What it means	Check first
P2452, P2453	DPF pressure sensor circuit; circuit range or performance	Blocked hoses, the sensor, its wiring and connector, and whether regeneration is working3
P2454, P2455	DPF pressure sensor circuit low, high	The sensor and its wiring; an exhaust leak can also set these2
P244A, P244B	Pressure across the filter too low, too high	Exhaust leaks before or near the sensor, leaks in its hose, modifications to the exhaust or engine3

A code tells a garage what to test, not which part to replace³. The other DPF codes, such as P2002, P2463 and P242F, are explained in our DPF fault codes guide.

Can I drive with a faulty DPF pressure sensor?

Only gently, and only as far as a garage. BM says the conditions behind P2452 and P2453 could lead to engine or fuel system damage and should be treated as a priority³. Without a believable reading, the engine computer may stop regenerating the filter or cut the power to protect the engine^3,5. Carry on like that and the filter keeps filling with soot. Once it is completely blocked, a regeneration can’t clear it, and it has to be cleaned off the vehicle or replaced² (see DPF cleaning: does it work, or do you need a new DPF?). A pipe costs a small fraction of that.

DPF pressure sensor faults and the NCT

The NCT manual says nothing about the DPF pressure sensor or its pipes, but the test does check what a fault often causes⁷:

• The engine warning light. Before the smoke test on a diesel, the tester runs some pre-checks. If the engine warning lamp indicates a defect, the smoke test is not carried out, and an engine warning light that stays on with the engine running is a major defect, so the vehicle fails⁷. Pressure sensor codes usually come with the engine warning light³, so fix the fault before the test.
• Smoke. Excess exhaust smoke likely to affect other road users is a fail, and so is a smoke meter reading above the limit: 1.5 m^-1 for diesels first registered after 1 July 2008 and 0.7 m^-1 for Euro 6 engines first registered after 1 September 2015, with higher limits for older diesels⁷. Black smoke is one of the symptoms BM lists for the pressure sensor codes P2452 and P2453³.
• Stored fault codes. The tester also plugs a scanner into the diagnostic socket. For now, an error code found that way gives an “Advisory Pass” rather than a fail, because the NCT is bringing in its on-board diagnostics checks in phases. The NCTS still strongly recommends having any error codes dealt with^7,8.

If the vehicle has already failed, see failed your NCT on emissions? What to do next.

Choosing the right DPF pressure pipe

We sell 333 pressure pipes for 36 makes, most of them for DPFs and a few for petrol particulate filters, catalytic converters and SCR units. Each pipe is made for particular filters: its page lists the vehicles it fits and where it goes, and each DPF’s page shows the pipes that go with it. Match three things:

• The vehicle and engine. Use our part finder or your vehicle’s page.
• The filter. If you are fitting a new DPF at the same time, choose the pipes listed on its page. Every DPF and catalytic converter we sell in Ireland is type approved: its part number has an H after the digits.
• The position. Many vehicles have two pipes, and they are different parts. Each pipe’s page says where it goes, for example pre-DPF or post-DPF, front or rear, short or long, and some are also sold as a pre- and post-DPF pair.

Some of the vehicles we have pipes for:

Vehicles (diesel)	Pressure pipes	For filter
Peugeot 206, 207, 307, 308, 3008, 407, 5008 and Partner, Citroën Berlingo, C3, C4, C4 Picasso and C5, MINI: 1.6, 2004 to 2012	PP11013A (front, short), PP11013B (rear, long)	BM11013H
Nissan Qashqai and X-Trail, Renault Megane, Scenic and Trafic, Opel Vivaro, Mercedes Vito: 1.6, 2011 to 2017	PP11290A (pre-DPF), PP11290B (post-DPF), PP11290C (pair)	BM11290H
Volkswagen Golf and Passat, Skoda Octavia and Superb, SEAT Leon, Audi A3: 1.6 and 2.0, 2014 to 2020	PP11381A (pre-DPF), PP11381B (post-DPF)	BM11381H
Ford Focus, C-Max, Mondeo, Galaxy and S-Max, Mazda 3 and 5, Volvo: 1.6, 2010 to 2015	PP11163A (front, short), PP11163B (rear, long)	BM11163H
Hyundai ix35 and i40, Kia Sportage, Optima and Carens: 1.7, 2010 to 2016	PP11183A (pre-DPF), PP11183B (post-DPF)	BM11183H
Toyota Yaris, Auris, Corolla, Verso S and Urban Cruiser: 1.4, 2008 to 2015	PP11243A (post-DPF)	BM11243H
Mercedes Sprinter: 2.1, 2009 to 2015	PP11461A (front, short), PP11461B (rear, long)	BM11461H
Peugeot Boxer and Citroën Relay 3.0, Fiat Ducato 2.3 and 3.0: 2006 to 2010	PP11099A (pre-DPF), PP11099B (post-DPF)	BM11099H

Years and models are a guide: each pipe fits particular engines within them, so check yours on the pipe’s page or with the part finder. Our pipes are the metal sections only; the rubber hoses and the sensor are separate parts. Whenever a DPF is fitted, BM’s advice is to check the rubber hoses for wear and fit new ones if necessary⁴.

What it costs

Our DPF pressure pipes cost €34.99 to €119.99, and half of them cost €54.99 or less. A type-approved DPF on its own costs €154.99 to €547.99, and a combined catalytic converter and DPF €207.99 to €1,142.99. These are our prices on 7 November 2026, in euro. They are export prices with no UK VAT: Irish VAT at 23% and any customs duty are collected by the courier before or on delivery, with its own clearance fee, and we show an estimate of the Irish VAT under each price. Delivery to the Republic of Ireland is €30.99 per order, whatever the size of the part; orders placed before 4pm on a working day are normally dispatched the same day, and the courier usually takes 2 to 3 working days. The details are on our Delivery page. More on filter prices in how much does a replacement catalytic converter or DPF cost?

Frequently asked questions

Can a DPF pressure sensor be cleaned?

The pipes and hoses can: if soot has blocked them, they are cleared or replaced². The sensor is an electronic part, and when it is faulty, the fix is a new one^2,6.

Will a new DPF fix a pressure sensor fault code?

No. A new filter should never be the cause of a fault code, and BM says DPF codes are rarely caused by the filter³. If a pipe, hose or the sensor is at fault, the code comes back with the new filter, and the new filter can block in turn².

Is the DPF pressure sensor the same as the exhaust pressure sensor?

Not always. A DPF differential pressure sensor compares the pressure before and after the filter^1,2. BM’s fault code guide lists a faulty DPF pressure sensor and a faulty exhaust pressure sensor as two separate causes of a soot code³, and some vehicles have another differential pressure sensor for the EGR system¹. Check which one a code or a part refers to.

Do I need new pressure pipes with a new DPF?

Not always. Check the old pipes for blockages and the hoses for wear, and fit new ones where needed⁴. A pipe that is blocked, cracked or badly rusted is worth replacing while the filter is off: it costs far less than the filter, and a false reading can block the new one².

Do I need to reset anything after replacing a pipe or the sensor?

Clear the fault codes and test-drive the vehicle⁵. After a new sensor, its offset has to be programmed into the engine computer²; the workshop data for your vehicle gives the procedure.

Will a DPF pressure sensor fault fail the NCT?

If it keeps the engine warning light on with the engine running, yes: the smoke test isn’t carried out and the vehicle fails⁷. A stored code found through the diagnostic socket currently gives an “Advisory Pass” instead^7,8.

Find the part

Search by vehicle with our part finder, browse all DPF pressure pipes, or start from your vehicle: Volkswagen Golf, Skoda Octavia, Ford Focus, Toyota Corolla, Nissan Qashqai, Kia Sportage, Peugeot 308, Citroën Berlingo, Opel Vivaro, Mercedes Sprinter or all vehicles. If the filter itself has to be replaced, see our DPFs and combined catalytic converter and DPF units, backed by our fitment guarantee.

Related guides: DPF regeneration explained, DPF fault codes explained, DPF cleaning: does it work? and how to replace a DPF.