P24B6

Diesel Particulate Filter Differential Pressure Sensor Circuit Low

P24B6 is a generic OBD-II powertrain diagnostic trouble code: Diesel Particulate Filter Differential Pressure Sensor Circuit Low. 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.

Code
P24B6
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on)
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What P24B6 means

P24B6 is set when the ECM detects that the voltage signal from the diesel particulate filter differential pressure sensor has dropped below the minimum expected operating range. This indicates an electrical fault in the sensor circuit rather than a performance or rationality issue. The ECM interprets the low voltage as a circuit fault and disables reliance on the sensor signal.

Common causes include a broken or shorted signal wire in the sensor harness, a failed sensor with an internally shorted signal element, a poor ground connection at the sensor, or a wiring harness fault caused by heat damage or abrasion near the exhaust system. A short to ground on the signal wire is a typical finding.

With the differential pressure sensor signal unavailable, the ECM may revert to a default soot model and inhibit active DPF regeneration monitoring. This can lead to undetected DPF over-loading, so the fault should be diagnosed and repaired promptly. The DPF system functionality is compromised until the sensor circuit is restored.

Common causes

Most-frequently reported root causes when P24B6 is logged.

  • 1
    Short to ground on the differential pressure sensor signal wire causing a low voltage reading.
  • 2
    Broken signal wire in the harness between the sensor and the ECM.
  • 3
    Defective differential pressure sensor with a failed internal signal element.
  • 4
    Corroded or loose connector at the sensor causing a low-resistance path to ground.
  • 5
    Wiring harness damage from heat, abrasion, or chafing near the exhaust system.
  • 6
    Poor ground connection at the sensor body or ECM ground reference.
  • 7
    Moisture ingress into the sensor connector causing a short circuit.

Symptoms drivers notice

MIL illuminated on the instrument cluster.
DPF soot load data unavailable or reading zero on the scan tool.
DPF regeneration may be inhibited or performed using a default model only.
No immediate drivability change unless the ECM enters a protective DPF strategy.
Possible DPF warning light if the ECM cannot confirm filter status.

How to diagnose P24B6

A typical diagnostic flow when this code is present.

  1. 1
    Read and record all DTCs and freeze-frame data with a scan tool.
  2. 2
    Inspect the differential pressure sensor wiring harness for visible damage, heat exposure, or chafing near the exhaust.
  3. 3
    Check the sensor connector for corrosion, moisture, or pushed-back terminals.
  4. 4
    Measure the sensor signal voltage at the connector with the ignition on; a reading below the minimum specification confirms the low circuit condition.
  5. 5
    Disconnect the sensor and recheck signal wire voltage at the ECM connector to isolate whether the fault is in the harness or the sensor.
  6. 6
    Repair or replace damaged wiring as found; replace the sensor if the harness checks out correctly.
  7. 7
    Clear DTCs and verify the sensor signal returns to the correct operating range after repair.

Related powertrain codes

Frequently asked questions

What voltage should the DPF differential pressure sensor signal read?

Reference voltage and expected signal range vary by sensor type and manufacturer. Always consult the vehicle-specific service manual for the correct specifications before testing.

Can P24B6 be caused by a sensor blocked with soot rather than a wiring fault?

No. P24B6 is specifically a low circuit voltage fault, which is electrical in nature. A blocked sensor port would typically cause a performance or rationality code rather than a circuit low code.

Is it safe to drive with P24B6 active?

The vehicle can usually be driven short-term, but DPF monitoring is compromised. Extended driving without a functioning pressure sensor risks undetected DPF overloading and potential filter damage.

Will replacing the sensor always fix P24B6?

Not always. If the wiring harness has a short to ground, replacing the sensor without repairing the harness will result in the new sensor immediately showing the same fault.

Disabling P24B6 in software

RaceTune can permanently disable P24B6 — 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.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

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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