P24B7

Code

Generic P — Powertrain

Particulate Matter Sensor Heater Resistance

Brand: Generic

Type: P — Powertrain

Views: UK: 22 EN: 155 RU: 26

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Page language: EN

Causes

Open or short in the PM sensor heater element
Corroded, loose, or damaged connector pins
Damaged wiring/harness (chafing, high resistance, broken conductor)
Poor or missing ground or power supply to heater circuit
Failed particulate matter sensor (internal heater fault)
Blown fuse or faulty relay feeding the heater circuit

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Diagnostic trouble code P24B7 stored in ECM
Possible loss of automatic DPF regeneration or altered regen strategy
Reduced emission control efficiency; vehicle may fail emissions test
In some systems: reduced performance or limp-home strategy if ECM limits operation

What to check

Retrieve freeze frame and live data with a scan tool; note occurrences and related codes
Visual inspection of PM sensor, connector, and wiring for damage, corrosion, or contamination
Check fuses and relays supplying the heater circuit
Measure voltage at the sensor connector with heater commanded ON and OFF
Measure heater circuit resistance (sensor unplugged) and compare to expected range
Perform wiggle test on harness while monitoring resistance/voltage for intermittent faults

Signal parameters

Heater supply voltage (V) at sensor connector when commanded ON
Heater current (A) when activated (if available via scan tool)
Measured heater resistance (Ω) across heater pins
PM sensor temperature (if provided) or calculated heater duty cycle
PM concentration or soot level readings from the sensor (where available)
ECM commanded heater status (ON/OFF/duty cycle)

Diagnostic algorithm

Read and record all stored and pending codes and freeze-frame data. Clear codes, then perform a road or function test to see if code returns.
Perform a thorough visual inspection of the PM sensor, connector and nearby wiring for heat damage, corrosion, contamination, pin push-out or water ingress. Repair visible damage.
With ignition OFF, disconnect the sensor and measure the heater element resistance at the sensor connector. Compare to manufacturer specification if available. Note: do not apply power when measuring continuity unless instructed.
Check resistance/continuity between the ECM heater-control output and the sensor connector to locate opens or high-resistance connections. Also check continuity to chassis ground where applicable.
With a scan tool, command the heater ON and measure heater supply voltage at the connector while monitoring heater current (if the tool supports it). Confirm ECM is commanding the heater and that supply voltage is present.
Perform a wiggle test on the wiring harness and connector while monitoring live data and heater resistance/voltage to find intermittent faults.
If wiring and connectors check good but resistance is out of range or heater does not draw current when commanded, replace the particulate matter sensor with a known-good unit and clear codes.
After repair or replacement, perform forced regen or required relearn procedures per manufacturer, and verify code does not return. If code returns with new sensor installed, suspect ECM or related control circuit fault and proceed with module-level diagnostics.

Likely causes

Corroded or water-damaged connector at the PM sensor
Open or degraded heater element inside the PM sensor
Damaged wiring harness between ECM and sensor (open or high resistance)
Failed sensor after long service or exposure to harsh conditions

Fault status

⚠️ Status

Stored when the ECM detects particulate matter sensor heater circuit resistance outside of expected limits. MIL illuminated; DPF/PM sensor heater operation may be disabled until fault is cleared and repaired.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours