P248E
Diesel Particulate Filter Restriction - Differential Pressure Too HighP248E is a generic OBD-II powertrain diagnostic trouble code: Diesel Particulate Filter Restriction - Differential Pressure Too High. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.
What P248E means
P248E is set when the ECM detects that the measured differential pressure across the diesel particulate filter has exceeded a maximum allowable threshold for the current operating conditions. This indicates a severely restricted filter where exhaust gas flow is being impeded to a degree that can affect engine breathing, turbocharger performance, and exhaust temperature management.
The differential pressure threshold used to set P248E is typically higher than the thresholds used for soot accumulation or ash accumulation codes. A reading this high usually indicates either a physically blocked DPF that has not responded to previous regeneration attempts, a filter that is packed with ash beyond its service limit, physical damage or collapse of the substrate causing a flow restriction, or a melted substrate caused by an uncontrolled regeneration event at extreme soot load.
Because excessively high exhaust backpressure directly impacts turbocharger efficiency and can cause elevated crankcase pressure, oil consumption, or damage to turbo seals, P248E is treated as a higher-urgency fault. The ECM may restrict engine output to protect the turbocharger and engine when this code is active. Diagnosis should confirm the actual physical state of the DPF before attempting any further regeneration.
Common causes
Most-frequently reported root causes when P248E is logged.
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1
Severely soot-loaded DPF that has not responded to regeneration attempts.
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2
DPF substrate fully loaded with ash beyond its rated service capacity.
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3
Physical damage to the DPF substrate causing collapse and flow restriction.
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4
Melted or fused DPF substrate caused by a thermal runaway during a late regeneration event.
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5
Faulty differential pressure sensor or blocked reference hoses generating a false high reading.
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6
Exhaust backpressure amplified by a separate downstream restriction such as a damaged muffler or catalyst.
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7
Incorrect DPF replacement with a unit of the wrong specification causing excessive restriction.
Symptoms drivers notice
How to diagnose P248E
A typical diagnostic flow when this code is present.
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1
Connect a scan tool and record all codes; assess the differential pressure live data value and compare to the maximum specification.
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2
Inspect the differential pressure sensor hoses for blockages before attributing the reading to the DPF itself.
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3
Verify sensor calibration by checking its output at idle against expected low-load values.
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4
If sensor and hoses are confirmed good, perform a visual inspection of the DPF for external damage, leaks, or signs of overheating.
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5
Attempt a stationary forced regeneration only if soot load is the suspected cause and no signs of physical damage are present.
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6
If regeneration does not resolve the fault or physical damage is suspected, remove and inspect the DPF for substrate integrity.
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7
Replace the DPF if substrate damage is confirmed or if ash loading has exceeded the cleanable limit.
Vehicles where we've handled P248E
Platforms in our catalogue with confirmed P248E coverage.
Related powertrain codes
- P2400 — Evaporative Emission System Leak Detection Pump Control Circuit/Open
- P2401 — Evaporative Emission System Leak Detection Pump Control Circuit Low
- P2402 — Evaporative Emission System Leak Detection Pump Control Circuit High
- P2404 — EVAP Leak Detection Pump Sense Circuit: Implausible Signal
- P2405 — Evaporative Emission System Leak Detection Pump Sense Circuit Low
- P2407 — Evaporative Emission System Leak Detection Pump Sense Circuit Intermittent/Erratic
Frequently asked questions
Can a forced regeneration fix P248E?
Possibly, if the restriction is due to recoverable soot loading. However if the differential pressure is at the level that triggers P248E, there is a risk that forced regeneration could cause thermal damage to an already stressed substrate. Confirm the physical condition of the DPF first.
What happens if I keep driving with P248E active?
Continued driving with severely elevated exhaust backpressure risks damage to turbocharger seals, increased crankcase pressure, elevated oil consumption, and potential catalyst or DPF thermal damage during any subsequent regeneration attempt. The fault should be addressed urgently.
Does P248E always mean the DPF needs replacement?
Not always. If the cause is a recoverable soot overload without physical damage, a successful forced regeneration may resolve the fault. If the filter has reached its ash limit, cleaning may restore it. Replacement is necessary only if the substrate is physically damaged.
Could a cracked DPF cause P248E?
A cracked substrate that has partially collapsed internally could cause a restriction severe enough to trigger P248E. A cracked DPF casing that creates a bypass path would more likely cause lower than expected differential pressure, so the type of crack matters for diagnosis.
Disabling P248E in software
RaceTune can permanently disable P248E — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.
ECUs with a P248E disable in our catalogue
Confirmed coverage from our recipe database — we support many more families. Upload your file and our identifier will match it automatically.
- Bosch EDC17C50 verified 1 software version
Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.
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