P244B - DPF Differential Pressure Too High

Quick Answer

• What this code means: The engine control module (ECM) has detected that the differential pressure across the Diesel Particulate Filter (DPF) is excessively high, indicating a blockage or malfunction within the DPF system.
• Severity: Get towed or repair immediately. Driving with this code can lead to further engine damage, reduced fuel economy, and potential complete DPF failure.
• Most common cause: A severely clogged Diesel Particulate Filter (DPF).

What the P244B code means

The P244B diagnostic trouble code (DTC) officially translates to "Diesel Particulate Filter Differential Pressure Too High." In simpler terms, your vehicle's computer has observed that the pressure difference between the inlet and outlet of the Diesel Particulate Filter (DPF) is much higher than it should be. This high differential pressure is a strong indicator that the DPF is clogged or has an internal issue restricting exhaust gas flow.

The DPF is a critical component in modern diesel vehicles, designed to trap particulate matter (soot) from the exhaust gas before it's released into the atmosphere. The pressure differential sensor monitors the pressure before and after the DPF to assess its loading. When this differential pressure becomes too high, it signifies that the filter is unable to effectively trap and burn off the soot, leading to a buildup that can severely restrict exhaust flow and damage the DPF or even the engine.

Common Symptoms

• Check Engine Light illuminated
• Reduced engine power or "limp mode"
• Poor fuel economy
• Excessive black smoke from the exhaust (in severe cases)
• Engine may enter regeneration cycles more frequently or fail to complete them
• Unusual odors from the exhaust
• Engine stalling or rough idling

Common Causes

1. Severely Clogged Diesel Particulate Filter (DPF): This is the most common cause. Over time, or due to failed regeneration cycles, the DPF can accumulate excessive soot and ash, leading to a blockage.
2. Faulty DPF Differential Pressure Sensor: The sensor itself might be providing inaccurate readings, leading the ECM to believe the pressure is too high when it isn't.
3. Damaged or Leaking Differential Pressure Sensor Hoses: Hoses connecting the DPF to the differential pressure sensor can become cracked, clogged, or disconnected, causing incorrect pressure readings.
4. Exhaust System Leaks Before or After the DPF: Leaks in the exhaust system can affect pressure readings and mimic a clogged DPF.
5. Malfunctioning DPF Regeneration System: Issues with the exhaust gas temperature sensors, oxygen sensors, fuel injectors (for post-injection), or the DPF igniter (if equipped) can prevent proper DPF regeneration, leading to soot buildup.
6. Incorrect Engine Oil or Fuel Additives: Using engine oil not compliant with low-ash specifications or certain fuel additives can contribute to DPF clogging.
7. Short Driving Cycles: Frequent short trips at low speeds may not allow the DPF to reach temperatures necessary for active regeneration, leading to soot accumulation.

How a technician diagnoses it

1. Verify the Code and Freeze Frame Data: The technician will connect an OBD-II scanner to confirm the P244B code and check for any other related codes. Freeze frame data will be analyzed to understand the engine operating conditions when the code was set, such as engine speed, load, and DPF temperatures.
2. Visual Inspection of the DPF and Related Components: A thorough visual inspection will be performed, looking for physical damage to the DPF, leaks in the exhaust system, and any damage or disconnections to the DPF differential pressure sensor hoses.
3. Monitor DPF Differential Pressure Sensor Readings: Using a scan tool, the technician will monitor live data for the DPF differential pressure. They will compare these readings at idle, during acceleration, and at steady highway speeds to manufacturer specifications. High pressure readings even under light load or at idle indicate a significant blockage.
   • Good values: Differential pressure typically increases with engine load but should remain within a specified range (e.g., 0-5 psi at idle, increasing to maybe 15-20 psi under heavy load, depending on the vehicle).
   • Bad values: Consistently high differential pressure (e.g., 20+ psi at idle or light load) is a strong indicator of a clogged DPF.
4. Perform DPF Regeneration (if possible): If the DPF is partially clogged, the technician may attempt to initiate a forced DPF regeneration using the scan tool. They will monitor exhaust gas temperatures and differential pressure during this process to ensure it completes successfully and reduces soot load.
5. Test DPF Differential Pressure Sensor: If readings are suspicious, the sensor's voltage output or resistance may be tested directly with a multimeter to ensure it's within specifications. The hoses connecting the sensor to the DPF will also be checked for clogs or damage.
6. Check Exhaust Gas Temperature (EGT) Sensors: Malfunctioning EGT sensors can prevent DPF regeneration. Their readings will be monitored for accuracy with the scan tool.
7. Advanced Diagnostics: In some cases, a backpressure test may be performed directly on the exhaust system to confirm DPF blockage, or borescope inspection of the DPF media may be necessary.

Typical Repair Cost

The cost to repair a P244B code can vary significantly depending on the underlying cause and the vehicle make and model.

• Clogged DPF (Cleaning/Forced Regeneration): $300 - $800 (parts and labor). This is often the cheapest solution if the DPF is not permanently damaged.
• DPF Differential Pressure Sensor Replacement: $200 - $500 (parts and labor).
• DPF Differential Pressure Sensor Hose Replacement: $100 - $300 (parts and labor).
• New Diesel Particulate Filter (DPF) Replacement: $2,000 - $7,000+ (parts and labor). This is the most expensive repair, often necessary if the DPF is severely or permanently damaged.
• Exhaust System Leak Repair: $100 - $500 (parts and labor), depending on the location and severity of the leak.

Can I keep driving with this code?

No, it is not recommended to keep driving with a P244B code. This code indicates a serious issue with your vehicle's Diesel Particulate Filter (DPF). Continued driving can lead to:

• Catastrophic DPF failure: A completely blocked DPF will eventually prevent exhaust gas from exiting the engine, potentially causing severe damage to the DPF beyond repair, necessitating a very expensive replacement.
• Engine damage: Restricted exhaust flow can lead to increased engine backpressure, which can cause turbocharger failure, exhaust valve damage, and other internal engine problems.
• Reduced performance and fuel economy: Your vehicle will likely operate in "limp mode," significantly reducing power and wasting fuel.
• Increased emissions: The DPF is crucial for emissions control. Driving with a faulty DPF means your vehicle is releasing harmful particulate matter into the atmosphere.

Get your vehicle inspected and repaired as soon as possible by a qualified technician.

Related Codes

• P244A: Diesel Particulate Filter Differential Pressure Too Low (could indicate a leak or faulty sensor)
• P2452: Diesel Particulate Filter Differential Pressure Sensor "A" Circuit
• P2453: Diesel Particulate Filter Differential Pressure Sensor "A" Circuit Range/Performance
• P2454: Diesel Particulate Filter Differential Pressure Sensor "A" Circuit Low
• P2455: Diesel Particulate Filter Differential Pressure Sensor "A" Circuit High
• P2002: Diesel Particulate Filter Efficiency Below Threshold (Bank 1)

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