Code result
P21B6
Cold Start Cylinder 1 Injection Timing
Moderate severity
What it means
Cylinder 1 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.
Is it safe to drive?
Use caution
The vehicle is usually drivable for short distances, but the problem can worsen or affect emissions. Diagnose and repair as soon as practical.
Most likely causes
Injector flow-rate aged
highOne of the most commonly reported causes for this code — check this first.
Crank/cam correlation off
mediumA plausible cause — test and verify before replacing parts.
Related help
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