What is the difference between P2452 and P2453?

P2452 is an electrical fault: the circuit reads open, shorted or out of range, so the control unit is getting no valid signal at all. P2453 means the signal is electrically fine but the value does not make sense — it does not sit near zero with the engine off, or does not change with exhaust flow, or contradicts the calculated soot model. That difference points at different repairs. The circuit code sends you to the plug and the wiring; the plausibility code sends you to the two sensing pipes, which are usually blocked, split or connected the wrong way round.

Can blocked DPF sensor pipes cause this code?

Yes, and it is the most common cause. The sensor reads the exhaust through two narrow pipes tapped in either side of the filter, and the one on the dirty side gradually clogs with soot. Once it does, the sensor cannot see the real pressure difference and reports something implausible. Removing and clearing the pipes is a quick job with no parts involved, which is why it should always be done before a sensor or a filter is condemned.

Will P2453 fail an MOT?

Yes, through the lamp, which is a major defect on diesels first used on or after 1 July 2008. There is a knock-on risk as well. A pressure signal that is wrong in either direction disrupts the filter's management: reading low means regenerations never run and the filter loads with soot, reading high means constant regeneration attempts that dilute the engine oil with diesel. Both can produce visible smoke, and a diesel fitted with a particulate filter fails on visible smoke of any colour as well as on the measured opacity limit.

Why is my oil level rising on a diesel?

Usually because regenerations are being started and not completed. A regeneration raises exhaust temperature by injecting extra fuel late in the combustion cycle, and some of that fuel washes past the piston rings into the sump. A cycle that completes burns the diesel back off; cycles that are repeatedly attempted or interrupted leave it there, and the oil level climbs while the oil itself thins. An oil level above the full mark on a diesel should be treated seriously, because thinned oil does not protect the engine and in extreme cases an engine can run on its own sump oil.

Powertrain code · standard

P2453Particulate filter pressure sensor reading implausible values

Standard definition: Diesel Particulate Filter Pressure Sensor Circuit Range/Performance

Last updated 27 July 2026

Quick answer

The sensor is electrically healthy but what it reports does not make sense. In practice that usually means the two small pipes running to the exhaust are blocked with soot, split, or connected the wrong way round — not that the sensor itself has failed, and not that anything is wrong with the filter.

How the car works this out

Unlike the circuit code, this is a plausibility check. A differential pressure sensor should read essentially nothing with the engine off, because there is no flow and therefore no pressure difference across the filter. It should then rise and fall predictably with engine speed and load. The control unit sets this code when the reported value does not fit: a reading well away from zero at rest, a negative reading when there should be positive pressure, a value that does not change as exhaust flow changes, or one that contradicts the calculated soot model and the temperature sensors.

What you might notice

Engine management lamp, often with the particulate filter lamp
Regenerations happening far too often, or not at all
An oil level slowly rising above the full mark, from repeated regeneration attempts putting diesel into the sump
Reduced power on some vehicles
A filter lamp that behaves inconsistently — clearing after a run, returning almost immediately

What causes it

Most likely first. A code names the check that failed, not the part that failed it, so more than one of these can produce the same number.

1The sensing pipes blocked with soot, particularly the pre-filter one which carries the dirtiest gasCommon
How to check: Disconnect both pipes and check they are clear. This is a five-minute job and it is a very common answer.
2Split, kinked, perished or heat-damaged sensing hosesCommon
How to check: Flex each hose along its length. The rubber sections perish where they meet the metal pipes and split there first.
3The two pipes connected the wrong way round after earlier work on the exhaust or turbochargerPossible
How to check: A reported pressure difference that goes negative as the engine is revved is the signature of reversed pipes, and correcting it costs nothing.
4The sensor drifting out of calibration with agePossible
How to check: Compare its reported value with the engine off. A sensor that cannot read close to zero at rest has drifted and will misjudge the filter across its whole range.
5Condensation collecting in the sensing pipes and freezing, which produces an intermittent fault confined to cold weatherPossible
6The filter genuinely being blocked or gutted, so the real pressure difference is itself outside what the control unit expectsPossible

What to do about it

1Take the two sensing pipes off and check them before doing anything else. Soot blockage and perished hoses account for a large share of these, and neither costs anything to inspect.
2Check what the sensor reports with the engine off. It should be close to zero, and if it is not, the sensor has drifted regardless of what the pipes look like.
3Confirm the pipes are on the correct ports if the exhaust or turbocharger has been worked on recently. Reversed pipes are a self-inflicted fault with a free fix.
4Check the engine oil level and smell it. A sensor under-reading causes missed regenerations, while one over-reading causes constant attempts, and the second of those puts diesel into the sump.
5Do not authorise a filter on this code alone. It is a code about the instrument, not about the thing being measured.

Can you keep driving?

Briefly, gently

The car will drive, but a wrong pressure reading is quietly damaging in whichever direction it errs. Under-reading means regenerations that never happen and a filter loading up unnoticed. Over-reading means regeneration cycles attempted constantly, which dumps unburnt diesel into the sump and thins the oil. Check the oil level and if it is rising above the full mark, stop driving it and get it seen to.

Will it fail an MOT?

The lamp fails the car as a major defect on diesels first used on or after 1 July 2008, but the reason this code is worth acting on before a test is that it corrupts the filter's management in both directions and each direction ends somewhere bad. A sensor reading low means regeneration never runs, the filter loads with soot, and a diesel fitted with a particulate filter fails on visible smoke of any colour, quite apart from the smoke opacity limit measured during the metered acceleration test. A sensor reading high means constant regeneration attempts, diesel accumulating in the engine oil, and a car that can smoke heavily during that test for a completely different reason. Neither is a fault to leave on the assumption that it is only a sensor.

The light this turns on

Diesel particulate filter lightThe diesel particulate filter has collected more soot than it can hold and needs to burn it off. Caught early this is fixed by a longer, faster drive; ignored, it turns into a blocked filter costing four figures.

Common questions

What is the difference between P2452 and P2453?: P2452 is an electrical fault: the circuit reads open, shorted or out of range, so the control unit is getting no valid signal at all. P2453 means the signal is electrically fine but the value does not make sense — it does not sit near zero with the engine off, or does not change with exhaust flow, or contradicts the calculated soot model. That difference points at different repairs. The circuit code sends you to the plug and the wiring; the plausibility code sends you to the two sensing pipes, which are usually blocked, split or connected the wrong way round.
Can blocked DPF sensor pipes cause this code?: Yes, and it is the most common cause. The sensor reads the exhaust through two narrow pipes tapped in either side of the filter, and the one on the dirty side gradually clogs with soot. Once it does, the sensor cannot see the real pressure difference and reports something implausible. Removing and clearing the pipes is a quick job with no parts involved, which is why it should always be done before a sensor or a filter is condemned.
Will P2453 fail an MOT?: Yes, through the lamp, which is a major defect on diesels first used on or after 1 July 2008. There is a knock-on risk as well. A pressure signal that is wrong in either direction disrupts the filter's management: reading low means regenerations never run and the filter loads with soot, reading high means constant regeneration attempts that dilute the engine oil with diesel. Both can produce visible smoke, and a diesel fitted with a particulate filter fails on visible smoke of any colour as well as on the measured opacity limit.
Why is my oil level rising on a diesel?: Usually because regenerations are being started and not completed. A regeneration raises exhaust temperature by injecting extra fuel late in the combustion cycle, and some of that fuel washes past the piston rings into the sump. A cycle that completes burns the diesel back off; cycles that are repeatedly attempted or interrupted leave it there, and the oil level climbs while the oil itself thins. An oil level above the full mark on a diesel should be treated seriously, because thinned oil does not protect the engine and in extreme cases an engine can run on its own sump oil.

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