P24F3
Reductant Tank Temperature/Fuel Temperature Correlation
After a long key-off soak the AdBlue/DEF tank temperature and the fuel tank temperature should read close to each other (both at ambient). The ECM detects an implausible spread, which usually means one of the two sensors drifts, is wired wrong, or has a heat source nearby that the plausibility model does not account for.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light or NOx warning on
- AdBlue/DEF level or quality warning
- Possible no-start countdown after ignore period
- Failed emissions inspection (NOx)
Common causes
Ordered by how often each turns out to be the cause.
- One temperature sensor drifting outside toleranceCommon
- Recently active reductant tank heater warming the tank above ambientPossible
Parts involved
- Reductant Tank Temperature Sensor
- Fuel Tank Temperature Sensor
P24F3 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.