P244A and P244B: DPF differential pressure too low or too high
P244A means the pressure drop across the filter is lower than a working filter should give; P244B means it is higher than a filter should ever reach. One points at a damaged or bypassed filter, the other at a blocked one, and both can be a sensor.
- Urgency
- Soon
- Reads the vehicle
- Your workshop
- Measures the filter
- Us
- Clean from
- ₹6,500
In plain words
P244A is "Diesel Particulate Filter Differential Pressure Too Low, Bank 1" and P244B is "Diesel Particulate Filter Differential Pressure Too High, Bank 1". They are set from the same sensor as the other DPF codes, but they describe the raw pressure reading rather than the computer's interpretation of it.
Too low means the exhaust is passing through the filter with less resistance than an intact substrate would give. That is either a cracked or melted filter, a filter that has been gutted, or a pressure line or sensor reading wrongly. Too high means the restriction is beyond what the regeneration logic is designed to handle, which is either a very heavily loaded filter or, again, a sensor or line fault reading high.
Usual causes, most common first
- 01P244A: a cracked, melted or collapsed substrate after an uncontrolled regeneration
- 02P244A: a filter removed and hollowed out by a previous workshop
- 03P244A: a split or disconnected upstream pressure line
- 04P244B: a filter heavily loaded with soot on top of ash, usually after a warning light driven through for weeks
- 05P244B: a blocked downstream pressure line or a sensor stuck high
In this order
Cheapest and least invasive first. Each step rules something out before you spend on the next.
Have your workshop inspect and blow through both pressure lines and check the sensor reading at key-on, engine off. This rules the cheapest cause in or out.
For P244B with reduced power, do not ask for a forced regeneration until the ash load has been read. At this level of restriction a burn can overheat the substrate.
Have the filter removed and sent to us. The before reading tells you whether it is damaged, blocked or fine.
For P244A with a damaged substrate, the filter is replaced, and the cause of the overheating that damaged it needs addressing so the new one survives.
What we find when the filter reaches us
Flow and back pressure are measured on arrival, before anything is quoted, and again after cleaning. Both readings go back with the filter.
- For P244A, the flow test settles it in minutes: a damaged or gutted substrate flows far too freely and is not a cleaning candidate; an intact filter with normal flow means the fault was the sensor or line
- For P244B, a genuinely blocked filter shows very high back pressure and recovers after cleaning; a filter that flows normally means the sensor was wrong
The symptom checker's view
The same pattern, scored from your answers. Each result links to the service that addresses it.
Asked about this one
Only if the substrate is intact, which the flow test shows. A filter reading too low because of a pressure line fault is fine and is not cleaned. A filter reading too low because it is cracked or melted cannot be repaired by cleaning, and we say so before any work.
Usually, yes: it is the code for a restriction higher than the regeneration logic will handle. But a blocked downstream pressure line gives the same reading on a clear filter, which is why the lines are checked first and the filter is measured rather than assumed.
Almost always from a regeneration on a filter that was too loaded for it: the soot burns hotter than the substrate can take, often during a forced regeneration on an ash-filled filter. Reading the ash load before any burn is how you avoid it on the replacement.
Related problems
All problems and codesSend the code and a photograph
A picture of the scanner screen or the dashboard message, the vehicle and mileage, and how it is behaving. You will get a straight answer on whether the filter is the problem, and what it costs to find out.