P244A is a common DPF temperature sensor fault code on Mercedes diesel models. It means the ECU has detected that the temperature sensor signal is outside the expected range – but that can be caused by a faulty sensor, a wiring issue, or a genuine temperature problem. This page breaks down the causes ranked by cost, what to check first, and whether you should keep driving.
P244A means the ECU is seeing an implausible signal from the DPF temperature sensor – typically because the sensor has failed, the wiring is damaged, or the sensor is reading a temperature that doesn't match expected values. On most Mercedes diesels, this is a sensor or wiring issue long before it indicates a DPF problem.
Do not assume the DPF itself is faulty – a simple £150 sensor replacement often fixes it. Full diagnostic order below.
In a Mercedes diesel equipped with a DPF (Diesel Particulate Filter), the ECU monitors exhaust gas temperature using one or more temperature sensors located before and after the DPF. P244A is logged when the signal from the DPF temperature sensor is outside the expected range – this could be due to a faulty sensor, a short or open circuit in the wiring, a poor connection, or a genuine temperature reading that is abnormally high or low. The code is a diagnostic flag, not a death sentence – it tells you the system has a temperature signal problem, but it doesn't tell you whether the sensor is faulty, the wiring is damaged, or the DPF is genuinely overheating. This code appears across the full range of Mercedes common-rail diesels, from the OM651 four‑cylinder to the OM642 V6 and the newer OM654, and the diagnostic approach is similar regardless of which engine triggers it.
Ordered by how often they are the real culprit – and by typical cost, so you can sanity-check any quote you've been given.
| Cause | Likelihood | Typical Cost (fitted) | Notes |
|---|---|---|---|
| Failed DPF temperature sensor | Very High | £100–£250 | Common failure; replacement is straightforward and inexpensive |
| Wiring harness damage or corrosion | Medium | £150–£400 | Corrosion or chafing can cause shorts or open circuits |
| Poor electrical connection / corroded plug | Medium | £50–£150 | Often the cheapest fix – cleaning or replacing the connector |
| Genuine DPF overheating or blockage | Low | £900–£1,500 | If the DPF is genuinely overheating, it may be blocked or damaged |
| ECU software issue or communication fault | Low | £200–£400 | Rare; sometimes resolved with a software update |
Cost figures [PATTERN DATA] – indicative independent‑specialist pricing, based on common Mercedes DPF sensor repairs.
Inspect the connector for corrosion, bent pins, or loose connections. Clean with contact cleaner – often resolves the issue.
A specialist can compare the DPF temperature sensor reading against other sensors (e.g., EGT sensor) to see if it's reporting plausibly.
Using a multimeter, test the sensor resistance against manufacturer specifications – often the quickest way to confirm a faulty sensor.
Test for continuity from the sensor connector to the ECU – a wiring break can cause the fault.
If the sensor and wiring are fine but temperature readings are still abnormal, the DPF itself may be blocked or damaged.
Our diagnostic wizard follows the same order, or confirm your engine with the registration lookup.
Conditionally, yes – but get it diagnosed within days. P244A on its own is not an engine-destroying fault, but if the ECU cannot read the temperature correctly, DPF regeneration may fail. Over time, this can lead to a blocked DPF and expensive repairs. Short journeys to a specialist are acceptable, but if the DPF warning light is also flashing or if the vehicle is in limp mode, prolonged driving is not recommended.
Short journeys to a garage are generally fine, but if the vehicle displays a DPF warning or has entered limp mode, you should get it checked promptly. Prolonged driving with an inaccurate temperature reading can prevent DPF regeneration and cause the filter to block.
No – wiring issues, corrosion, or poor connections are also common. A simple connector clean or a £150 sensor replacement often fixes it.
Only if the underlying problem is temporary (e.g., a one-off connection glitch). The code will return if the fault persists, and clearing it may destroy freeze‑frame data that helps diagnosis.
Expect £100–£250 at an independent Mercedes specialist – parts are inexpensive and labour is typically under 1 hour.
For Mercedes, the repair‑to‑value threshold is 70% – if the cost of the repair (including diagnostics and parts) exceeds 70% of the car's current market value, scrapping may be the more sensible financial decision. Always get a current valuation before committing to major work.
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