Code result
P04D9
Closed Loop EGR Control At Limit Flow Too Low
Moderate severity
What it means
With EGR running in closed loop the controller has driven the actuator to its maximum opening but cannot reach the required EGR flow. The valve, cooler, or pipework is restricted enough that even full open does not deliver the modelled rate.
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
EGR cooler clogged with soot
highOne of the most commonly reported causes for this code — check this first.
Valve effective opening reduced by carbon
mediumA plausible cause — test and verify before replacing parts.
Related help
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