P239D
Diesel Intake Air Flow B Control System Low Air Flow Detected
Same as P239C with the airflow below the threshold when the valve is commanded open - valve does not open fully or the path is restricted.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Valve does not open fullyCommon
Parts involved
- Diesel Intake Air Flow B
P239D 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.