Code
P243B
Generic
P — Powertrain
Particulate Filter Restriction - Forced Limited Power Bank 2
AI status
Completed
Completed
100%
Causes
- Clogged/sooted diesel particulate filter (DPF)
- Failed or contaminated differential pressure sensor across the DPF
- Faulty exhaust temperature sensors or wiring
- Exhaust leak upstream of the pressure/temperature sensors
- Failed turbocharger or boost system fault causing poor regeneration
- Incomplete or failed regeneration cycles
Symptoms
- Reduced engine power / limp-home mode active
- Illuminated MIL / DPF warning lamp
- Frequent or continuous regeneration requests with no successful regen
- Poor acceleration and decreased fuel economy
- Black smoke during acceleration (possible soot bypassing)
- Unusual exhaust/backpressure noise
What to check
- Read all stored and pending DTCs and freeze frame data with a capable scan tool.
- Check live data: DPF differential pressure, exhaust temps before/after DPF, soot load, and commanded regen status.
- Visually inspect differential pressure and temperature sensors, connectors, and wiring for damage or corrosion.
- Inspect exhaust system for leaks or damage upstream of the DPF (including turbo and downpipe).
- Confirm turbocharger and boost system integrity (hoses, intercooler, clamps).
- Check for related engine faults that prevent regen (fuel system, EGR faults, misfire codes).
Signal parameters
- DPF differential pressure (kPa or mbar)
- Soot load / DPF fill percentage or calculated soot mass (g)
- Exhaust temperature before DPF (°C)
- Exhaust temperature after DPF (°C)
- Turbocharger boost pressure / intake manifold pressure (kPa)
- Commanded regeneration active flag and timer
Diagnostic algorithm
- Capture full DTC list and freeze-frame. Note conditions (engine speed, load, temperatures) when fault set.
- Inspect connectors and wiring to DPF differential pressure and exhaust temp sensors. Repair any damage.
- Check for exhaust leaks between turbo and DPF. Repair leaks before retesting.
- Use scan tool to monitor differential pressure and exhaust temps at idle and during road load. Compare to manufacturer limits.
- Command an active regeneration while monitoring temps and differential pressure. Verify exhaust temp rises and differential pressure falls after regen.
- If active regen does not complete or differential pressure remains high, check turbo/boost system and fuel system for faults that prevent proper regen temperatures.
- If sensors are out of range or show inconsistent signals, test and replace faulty sensors; recheck system operation.
- If sensors and supporting systems are good but DPF remains heavily restricted after attempted regen, perform a forced DPF clean (manufacturer-approved procedure) or removal and off-vehicle cleaning as required.
- If cleaning fails or DPF damage is found, replace the DPF. Clear codes and verify repair with a road test and live-data monitoring.
- After repair/cleaning, confirm no pending or permanent codes and that regeneration cycles complete normally.
- Safety note: follow safe procedures for high-temperature components and use proper tooling/equipment for forced regens and DPF removal.
Likely causes
- High soot loading in DPF from long short-trip operation or oil burning
- Differential pressure sensor out-of-spec or intermittent (false high pressure reading)
- Exhaust temperature sensor out-of-range causing regeneration not to initiate
- Exhaust leak between turbo and DPF causing incorrect sensor readings
- Turbo underboost or intake leaks preventing required combustion temps for regen
- DPF physically damaged internally or catalytic substrate collapsed
Fault status
Status
Particulate Filter Restriction detected on Bank 2 — ECM has limited engine power to protect aftertreatment system.
Repair difficulty: Hard
Diagnostic time: 1.0-4.0 hours
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