P24B2

Code

Generic P — Powertrain

Particulate Matter Sensor Circuit Intermittent

Brand: Generic

Type: P — Powertrain

Views: UK: 22 EN: 41 RU: 23

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Page language: EN

Causes

Damaged, chafed, or broken wiring harness between PM sensor and control module
Loose, corroded or contaminated connector pins at sensor or ECU
Poor or intermittent ground or reference voltage
Contaminated or failed particulate matter sensor
Intermittent internal sensor electronics or heater circuit fault (if equipped)
Moisture/soot ingress or connector short caused by environmental contamination

Symptoms

Malfunction Indicator Lamp (MIL) illuminated intermittently
Intermittent DPF-related warnings or failed regen attempts
Inaccurate soot/load readings or fluctuating PM sensor live data
Occasional reduced engine performance or forced regen depending on strategy
Possible stored intermittent code(s) without constant faults

What to check

Scan tool: read freeze frame and historic data; monitor PM sensor live values while driving and during regen
Visually inspect PM sensor, connector, and wiring for chafing, heat damage, soot, or corrosion
Wiggle test harness and connectors while watching live data for intermittent changes
Backprobe connector: verify sensor supply/reference voltage and ground stability
Measure signal with DVOM and preferably oscilloscope to capture intermittent/pulse behavior
Check continuity and resistance between sensor pins and ECU pins; check for shorts to ground/power

Signal parameters

Supply/reference: typically an ECU-supplied reference (commonly ~5 V) or switched supply depending on design
Signal type: may be analog voltage, frequency/pulse, or digital data depending on sensor design
Expected behavior: stable signal appropriate to soot concentration; no random dropouts or noise
Intermittent fault indications: open circuit, short to ground/power, erratic voltage spikes, loss of signal
Use an oscilloscope to view transient interruptions or noise that a DVM may miss

Diagnostic algorithm

Connect a scan tool, record freeze frame and live PM sensor values; note operating conditions when fault set.
Clear code and perform a drive/recreate procedure to see if code returns and under what conditions.
Visually inspect sensor, connector, and harness for physical damage, soot intrusion, or corrosion. Repair as needed.
Backprobe sensor connector: verify reference voltage, ground continuity, and signal while key ON and during engine operation.
Perform a wiggle test on wiring/connectors while monitoring live data to reproduce intermittent behavior.
If intermittent signal seen, use an oscilloscope to capture transient faults; if none, measure continuity and insulation resistance between sensor and ECU.
Repair or replace damaged wiring, pins, or connectors. Clean and secure connectors; apply dielectric grease after repairs.
If wiring and connectors check good, replace the PM sensor with a known-good unit and re-test.
If code persists after sensor replacement, inspect ECU connector and grounds, review wiring diagram for shared circuits, and consider ECU fault diagnosis.
After repair, clear codes and verify through a full test/drive cycle and confirm no recurrence.

Likely causes

Corroded/dirty connector at PM sensor
Wiring damage near DPF, flex points, or heat-exposed areas
Intermittent ground or reference feed to sensor
Failed PM sensor (internal intermittent)
Intermittent ECU input or connector fault

Fault status

⚠️ Status

Particulate Matter Sensor Circuit — Intermittent fault detected. MIL may be illuminated. Inspect sensor wiring, connectors, grounds and sensor; monitor live data and perform continuity/oscilloscope checks.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 3.0 hours