P24B4
Particulate Matter Sensor Heater Control Circuit Range or Performance
Same as P24B3 with the heater control loop in plausible range yet not matching the heater model. The sensor heater warms the element to operating temperature (~600 °C); without it the lambda sensor stays inactive in closed loop and the ECM cannot trim mixture.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Heater element agedCommon
Parts involved
- Particulate Matter Sensor Heater
P24B4 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.