P24FE
SCR Catalyst Incorrect
The ECM identifies the installed SCR catalyst as the wrong part — NOx conversion efficiency, NH3 storage capacity or coded part-number do not match the expected application. Typical after fitting a non-OEM SCR brick or after a coding error following replacement.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Symptoms
- Check engine light on
- Failed emissions inspection
- Possibly slightly increased fuel consumption
- Sulfur (rotten egg) smell from exhaust under load
Common causes
Ordered by how often each turns out to be the cause.
- Incorrect or non-OEM SCR catalyst installedCommon
- Coding mismatch after part replacementPossible
Parts involved
- SCR Catalyst
P24FE 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.