Powertrain, generic (extended)

P24B4 Particulate Matter Sensor Heater Control Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P24B4 is a plausibility check on the heater of the particulate matter sensor, and makers apply it differently. Ford's 2023 diesel summary looks during measurement, with the heater switched off, and sets the code if heater voltage still exceeds 7 V for 2 s. GM's 14OBDG04 table uses the heater to confirm that exhaust actually reaches the element inside its protection tube: if heater voltage varies by less than 100 % while exhaust velocity is above 30 m/s, the result is a Type B fault. GM's 16OBDG04 instead times how long the heater needs to reach the regeneration setpoint and lists P24B4 as Type X without MIL. A blocked protection tube, a weak heater or extra resistance in the harness can all set it. P24B3, P24B5 and P24B6 cover the pure circuit faults.

Likely causes

Protection tube of the sensor blocked by soot or deposits
Heater element aged and heating too slowly
Extra resistance in the heater harness
Heater output in the sensor control unit not switching off

Symptoms

  • Malfunction indicator lamp on (not with every manufacturer)
  • Particulate filter monitor does not complete

Repair estimate

DifficultyMediumDIY possible
Parts and labour€150–700
Time0.5–2 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

particulate matter sensor heater

Related codes

P24B3P24B5P24B6P24B7

References: fordservicecontent.com, gsi.ext.gm.com, gsi.ext.gm.com.