P21BC
Cold Start Cylinder 7 Injection Timing
Cylinder 7 cold-start injection timing is outside the calibrated window. Diesel cold-start uses adapted injection timing per cylinder to limit white smoke and noise; deviation typically points at a worn injector or faulty crank/cam correlation.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: hard
Common causes
Ordered by how often each turns out to be the cause.
- Injector flow-rate agedCommon
Parts involved
- Fuel Injector
P21BC 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.