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P244B – Diesel Particulate Filter Differential Pressure Too High

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Understanding OBD-II Code P244B: Diesel Particulate Filter Differential Pressure Too High

How Urgent is P244B?

Code P244B indicates that the differential pressure across the diesel particulate filter (DPF) is higher than expected. While not immediately critical, it's best to diagnose and fix this issue promptly before it leads to more severe problems. Continuing to drive with P244B active risks damage to the DPF and reduced engine performance.

In our workshop, we've seen the P244B code pop up quite frequently on various European diesel vehicles, especially Volkswagen, Audi, BMW, and Mercedes models. The most common causes we've found are a clogged DPF due to infrequent regeneration, faulty differential pressure sensors, and leaks in the exhaust system. We've had success cleaning the DPF if it's not too far gone, but in severe cases replacement is necessary. Whenever this code appears, we also make sure to check the pressure sensor hoses and wiring for issues, as those can sometimes trigger a false P244B. Proper diagnosis is key to avoiding unnecessary parts replacement.

Code Details

P244B is a generic powertrain code that applies to diesel vehicles equipped with a DPF. The code definition is:

Some vehicle makes may have manufacturer-specific variants of this code with slightly different definitions. Always consult the factory service information for the exact code meaning.

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System Operation

The DPF traps soot from the exhaust to reduce emissions. Differential pressure sensors monitor the pressure drop across the DPF to infer soot loading.

There are two main types of differential pressure sensing setups:

  1. Single differential pressure sensor with hoses to measure pressure before and after the DPF
  2. Two absolute pressure sensors, one pre-DPF and one post-DPF

The powertrain control module (PCM) monitors the pressure readings and triggers code P244B when the difference exceeds a calibrated limit, indicating a restricted DPF.

Common Causes

Potential causes of excessive DPF differential pressure include:

Diagnosis Steps

  1. Scan for all codes. Note additional codes that may help pinpoint the cause.
  2. Inspect the pressure sensor hoses for restriction, damage, or leaks. Blockages are common.
  3. Check wiring and connectors to the pressure sensor(s) for faults per manufacturer diagnostic procedures.
  4. If hoses and wiring check out, evaluate DPF soot loading via a forced regeneration or soot mass calculation.
  5. An exhaust back pressure test can help confirm a restricted DPF.
  6. If the DPF is not restricted, suspect a faulty pressure sensor. Compare readings to known good values.

Repair Solutions

Prevention

Repair Costs

DPF pressure sensor replacement: $150-400 / €130-350
DPF cleaning service: $400-800 / €350-700
DPF replacement: $1000-3000 / €900-2600

P244B may occur in conjunction with:

Frequently Asked Questions about P244B

What does OBD-II code P244B mean?

Code P244B indicates that the differential pressure across the diesel particulate filter (DPF) is higher than expected, as detected by the pressure sensors and powertrain control module (PCM). This suggests the DPF is becoming restricted.

How serious is code P244B? Is it safe to keep driving?

While not immediately critical, it's best to diagnose and fix P244B promptly before it leads to more severe problems. Continuing to drive risks damage to the DPF and reduced engine performance. Get it checked out soon.

What are the common causes of code P244B?

Common causes include:

What are the symptoms of code P244B?

Often the only symptom is an illuminated check engine light. In some cases, you may notice decreased engine performance or fuel economy if the DPF is severely restricted.

How do you diagnose code P244B?

Key diagnostic steps:

  1. Scan for all codes to see if others may help pinpoint the cause
  2. Visually inspect pressure sensor hoses for damage or blockage
  3. Check pressure sensor wiring and connectors
  4. Evaluate DPF soot loading via forced regen or soot mass calculation
  5. Perform an exhaust back pressure test to confirm DPF restriction
  6. Test pressure sensor readings against known good values

Can code P244B be caused by a faulty pressure sensor?

Yes, a failing differential pressure sensor can falsely indicate a restricted DPF, triggering code P244B. Always verify the DPF is actually restricted before replacing it.

How do you test the differential pressure sensor?

Compare the sensor voltage readings to the manufacturer's expected values at various engine loads. Readings outside of specs suggest a faulty sensor. A smoke test can also reveal leaks in the sensor hoses.

What is the fix for code P244B?

It depends on the diagnosed cause:

Can I clean the DPF myself or does it need to be replaced?

Many repair shops can clean a soot-overloaded DPF using specialized equipment, which is much cheaper than replacement. However, DPFs eventually get ash-loaded over time and cleaning may no longer restore them, necessitating replacement.

How much does it cost to replace a DPF pressure sensor?

Expect to pay anywhere from $150-400 for a DPF differential pressure sensor replacement. Always go with an OEM or high-quality aftermarket sensor.

How much does it cost to clean or replace a DPF?

A professional DPF cleaning typically runs $400-800. If the DPF is damaged or ash-loaded and needs replacement, it can cost $1000-3000 depending on the vehicle.

How often should the DPF be cleaned?

DPFs are designed to go 100,000 miles or more between cleanings in ideal conditions. However, frequent short trips, excessive idling, or engine mechanical issues can accelerate soot loading. Follow the manufacturer's recommended cleaning interval for your vehicle's duty cycle.

Can I remove the DPF instead of replacing it?

No, it is illegal to remove the DPF in most jurisdictions as it will allow excessive soot emissions. Removing emissions control devices often violates the Clean Air Act and can result in substantial fines.

What happens if I ignore code P244B?

Ignoring a restricted DPF for too long will reduce engine performance and fuel economy as exhaust backpressure increases. This puts excess strain on the turbocharger and engine. Eventually, the DPF may become so restricted that the engine goes into limp mode or stalls.

How can I prevent DPF problems?

Tips to prevent P244B and other DPF issues:

What other codes may be related to P244B?

P244B may appear with other DPF-related codes like:

What tools do I need to diagnose P244B?

At minimum you'll need an OBD-II code scanner to read codes and view live sensor data. A smoke machine and exhaust backpressure tester are helpful for confirming leaks or restriction. Always refer to the factory service information for the proper diagnostic procedures.

Can low quality diesel fuel cause DPF problems?

Yes, poor quality diesel with high sulfur content or contaminants can accelerate soot and ash loading in the DPF, leading to restriction. Stick to reputable fuel stations and consider an anti-gel additive in winter.

Will the DPF clean itself if I go on a long highway drive?

It depends how restricted it is. If the DPF is only lightly soot-loaded, a long highway drive generating high exhaust temperatures may allow it to perform a passive regeneration and burn off the soot. However, if it's severely restricted, a manual regeneration with a scan tool or DPF cleaning may be needed.

How do I know if my vehicle has a DPF?

All diesel vehicles sold in North America after 2007 have a DPF to meet emissions standards. Some large trucks use a different type of particulate filter. Check your owner's manual or the emissions label under the hood to confirm.

Hopefully this FAQ has provided the key information you need to understand and resolve code P244B. Remember, when in doubt, consult with a professional technician who has experience diagnosing diesel emissions systems.

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