P24B4Particulate Matter Sensor Heater Control Circuit Range/Performance
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- Malfunction indicator lamp on (not with every manufacturer)
- Particulate filter monitor does not complete
- Likely causes
- PossibleProtection tube of the sensor blocked by soot or deposits
- PossibleHeater element aged and heating too slowly
- PossibleExtra resistance in the heater harness
- RareHeater output in the sensor control unit not switching off
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €150 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.