Powertrain, generic (extended)

P24B6 Particulate Matter Sensor Heater Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modeNo

P24B6 reports the heater of the particulate matter sensor carrying current although it is commanded off, the classic sign of a battery-side short or a stuck driver stage in the sensor control unit. GM's 18OBDG04 table sets it when more than 0.2 A flows with the heater off or when the switch state disagrees with the command in one of the last five readings, Type B. GM's 14OBDG04 checks the heater voltage in the off state. VW's 2014 Touareg list names a current of 0.2 A or more. A heater that stays on can overheat and crack the ceramic element, so the sensor often has to be replaced together with the wiring repair. P24B5 covers a short to ground, P24B3 an open line, P24B4 implausible heater behaviour.

Likely causes

Heater line shorted to battery voltage
Heater output stage in the sensor control unit stuck on
Sensor element damaged by uncontrolled heating

Symptoms

  • Malfunction indicator lamp on
  • Particulate filter monitor does not complete
  • Sensor may fail again quickly if the short is not fixed

Repair estimate

DifficultyMediumDIY possible
Parts and labour€100–800
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

P24B3P24B4P24B5P24B7

References: gsi.ext.gm.com, gsi.ext.gm.com, static.nhtsa.gov.