P24DC: Reductant Purge Control Valve B Performance
Standardized SAE J2012 code · P24xx — Auxiliary emission controls
What does P24DC mean?
Same as P24DB with the actuator electrically intact yet not delivering the commanded purge flow. Valve B is the second purge valve on systems that use two. The purge valve opens a path so that, after the engine is switched off, the dosing system can draw the remaining urea solution out of the dosing valve and lines; this protects them from freezing, as DEF freezes at about −11 °C, and from crystal deposits. If the valve cannot be controlled, the lines may stay filled, which risks frozen or blocked dosing parts and later SCR faults.
The code tells you which monitor failed, not which part is broken. Test before replacing parts.
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
- High Purge valve sticking
Likelihood is a general estimate across vehicles; your make and model may differ.
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