The DPF pressure differential has exceeded the maximum threshold. This is a warning that the particulate filter is becoming blocked — and if ignored, it leads to a much more expensive diesel particulate filter replacement, not just a regeneration.
P244A means the exhaust back-pressure sensor has detected too much pressure in the diesel particulate filter. The most common real cause is insufficient active regeneration from frequent short trips. The next is a failing differential pressure sensor.
Do not let anyone quote you for a new DPF before an attempt at forced regeneration has been made. Diagnostic order below.
In a diesel BMW, the exhaust system uses a differential pressure sensor to monitor the soot load in the Diesel Particulate Filter. P244A is triggered when the pressure difference across the DPF exceeds the maximum threshold. This is the DPF equivalent of a redline — it tells you the filter is so blocked that normal passive or active regeneration may no longer be possible. On modern BMW diesels, this is often the result of repeated short journeys that never get the exhaust hot enough to burn off trapped soot. The code is common across the N47, B47, N57 and B57 engine families. A forced regeneration by a BMW specialist can clear it, but if the filter is truly full of ash from high mileage, it's a replacement job — and the P244A is the signal that tells you which outcome is more likely. This code should always trigger an immediate response — not because it’s engine‑destroying, but because the cost gap between a forced regen (£250) and a replacement (£1,500+) is very large.
Ordered from most likely to least likely, with typical costs for each. This is the order a BMW specialist will work through.
| Cause | Likelihood | Typical Cost (fitted) | Notes |
|---|---|---|---|
| Blocked DPF due to urban driving | Very High | £250–£450 (forced regen) | Most common on cars that rarely see motorways |
| Failing differential pressure sensor | Medium | £180–£380 | Reports a false high reading; the filter may actually be fine |
| Temperature sensor failure (exhaust gas) | Medium | £200–£450 | Prevents the car from starting a regeneration cycle |
| DPF ash loading (high mileage) | Medium | £1,200–£2,200 | True end-of-life — the filter is full of ash that won't burn |
| Injector issue over-fueling | Low | £400–£1,200 | Can lead to excessive soot generation and rapid DPF block |
Cost figures [PATTERN DATA] — indicative independent-specialist pricing, not drawn from our engine replacement dataset.
A BMW specialist will use diagnostic software (ISTA or Autologic) to read the actual soot load and ash mass in the filter.
If soot load is the issue, a forced regen will burn off the trapped soot. This takes about 45 minutes and resolves the code in many cases.
Live data readings at idle vs. under load. A sensor reporting implausible pressure can be replaced without touching the filter.
If the EGT sensors are reading incorrectly, the car won't initiate a regen. This is an easy fix.
If ash mass is high, or the filter is physically damaged, a new DPF is the only fix.
Our diagnostic wizard walks the same order, or check your car's details with the registration lookup.
Yes, but treat it as urgent. P244A on a BMW is not an immediate engine-destroying fault — the engine is overheating, the exhaust is just becoming blocked. But if you continue to drive without addressing it, the DPF will clog further, the engine management light will flash, and the car will enter limp mode to protect the engine. Driving in limp mode at motorway speeds is hazardous because you won't have acceleration to merge or overtake. Prolonged driving with P244A can also lead to oil dilution from failed regeneration attempts, which can damage the engine. Get it looked at within a few days — a forced regen is cheap, a new DPF is expensive. On N47 and B47 engines, the DPF is more accessible than on some V6 units, so even replacement is a routine job for a BMW specialist. Do not ignore this code.
Yes, for short journeys — but not for extended motorway use, especially if the car has gone into limp mode. Prolonged driving with a blocked DPF can cause oil dilution and damage the engine.
No. In most cases, a forced regeneration (which costs a couple of hundred pounds) will clear the fault. Replacement is only necessary if the filter is physically damaged or full of ash that cannot be burned off.
It ranges from £250–£450 for a forced regeneration, to £1,200–£2,200 for a full DPF replacement. A failing sensor sits in the middle at around £180–£380.
You can trigger a regeneration by driving at 60 mph in a lower gear to keep the revs above 2,500 rpm for at least 20 minutes. But this may not clear the fault if the soot load is too high or the sensors are failing.
Cheapest-First AlwaysWe rank causes by likelihood and cost, not by what's profitable to quote.
Honest About CostWe don't scare you into a new DPF; a forced regen can often fix it.
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