The DPF differential pressure sensor 'B' circuit is reporting a range or performance issue. This often means a faulty sensor, but it can also point to a blocked DPF or a wiring problem. We break down the real causes and the cheapest diagnostic order.
P244B means the engine control unit has detected an out-of-range signal from the DPF differential pressure sensor (Bank 'B'). In most BMW diesels, this is a sensor or wiring fault — not a blocked filter. A replacement sensor typically costs £180–£380 fitted [PATTERN DATA].
Do not let anyone sell you a new DPF until the sensor and wiring have been ruled out. Full diagnostic order below.
In a BMW common-rail diesel, two differential pressure sensors (A and B) are sometimes used to monitor soot loading in the DPF. P244B refers specifically to the 'B' sensor — the one that measures pressure across the filter. When the ECU sees a voltage or resistance reading that falls outside the expected range, it sets this code. Importantly, the code does not mean the DPF is blocked — it means the sensor signal is unreliable. The pressure itself might be perfectly normal, but if the sensor is faulty or the wiring is damaged, the ECU can't trust it. That distinction is the difference between a £180 sensor and a £1,500 DPF, and it's why the diagnostic order below is so important. This code is common across N47, B47, N57 and B57 BMW diesel engines, and the diagnostic approach is essentially identical regardless of which engine triggers it. On N47 and B47 engines, the sensor is relatively accessible; on N57 units it can be a little more buried, but replacement is still a routine job for a BMW specialist.
Ordered by how often each is the real culprit, with typical fitted costs. This is the order a BMW specialist will work through.
| Cause | Likelihood | Typical Cost (fitted) | Notes |
|---|---|---|---|
| Failed differential pressure sensor (Bank B) | Very High | £180–£380 | Most common; sensor fails electrically or becomes clogged with soot |
| Wiring or connector issue (corrosion, chafing) | Medium | £100–£250 | Often intermittent; inspection and repair may be cheaper than replacement |
| Blocked DPF causing sensor to read incorrectly | Medium | £250–£450 (forced regen) or £1,200–£2,200 (new DPF) | The sensor may be fine; the filter is genuinely full |
| Software / calibration issue (rare) | Low | £80–£150 (reflash) | Sometimes a software update resolves the range/performance code |
| Exhaust leak affecting pressure readings | Low | £150–£500 | A leak upstream or downstream can skew the sensor's measurement |
Cost figures [PATTERN DATA] — indicative independent-specialist pricing, not drawn from our engine replacement dataset.
Inspect for corrosion, damage, or loose pins. Many P244B codes are caused by simple wiring faults that cost almost nothing to fix.
A specialist will compare the pressure readings from Sensor A and B at idle and under load. If B is consistently reading implausibly, it's likely faulty.
If the sensors are identical, swapping them can confirm a sensor fault — if the code moves to the other bank, replace the sensor.
Use diagnostic software to read actual DPF pressure and calculated soot mass. If the pressure is high and soot load is excessive, a forced regen may be needed.
If the sensor is confirmed good, wiring is intact, and the DPF is truly blocked with ash, replacement is the only option.
Our diagnostic wizard walks the same order, or check your engine with the registration lookup.
Yes — in most cases, it's safe to drive short distances. P244B on its own is not an engine-destroying code. The ECU may limit performance to protect the DPF, but you won't cause immediate damage. However, if the code is accompanied by a flashing glow-plug light or the car enters limp mode, you should avoid motorway driving and get it looked at within a few days. Prolonged driving with a faulty sensor can lead to incorrect regeneration cycles, which may eventually clog the DPF — turning a cheap sensor repair into an expensive filter replacement. On B47 and B57 engines, the sensor is relatively easy to replace; on N57 it's a little more labour-intensive, but still a manageable job for a specialist. Get it diagnosed promptly — the cost gap between a sensor and a DPF is large.
Yes, for short journeys — but not for extended motorway use if the car has gone into limp mode. Prolonged driving with a faulty sensor can lead to incorrect DPF regenerations and eventual blockages.
No. In most cases, the sensor or wiring is at fault. Replacement of the sensor (around £180–£380) is far cheaper and resolves the code in the majority of cases.
It ranges from £100–£250 for wiring repairs, £180–£380 for a sensor replacement, and up to £1,200–£2,200 for a full DPF replacement if the filter is genuinely blocked.
Only temporarily. The code will return if the underlying fault (sensor, wiring, or DPF) is not addressed. Clearing it also erases freeze-frame data that a specialist would use to pinpoint the cause.
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 sensor is often the only fix.
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