P24CB
Reductant Tank Cap Switch Circuit
A general circuit fault on the AdBlue tank cap switch - reports whether the cap is properly closed.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: easy
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.
- Open in switch or wiringCommon
Parts involved
- Reductant Tank Cap Switch
P24CB 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.