Code result
P204F
Reductant System Performance
High severity
What it means
The SCR (selective catalytic reduction) system using AdBlue/DEF is not delivering the expected NOx conversion. Causes range from poor reductant quality, dosing module faults, heater failure on the AdBlue tank in cold weather, or a degraded SCR catalyst.
Is it safe to drive?
No — stop driving
This code can put the vehicle into limp or reduced-power mode. Avoid extended driving and have the vehicle diagnosed promptly.
Most likely causes
Poor reductant quality or contamination
highOne of the most commonly reported causes for this code — check this first.
Dosing module clogged with urea crystals
mediumA plausible cause — test and verify before replacing parts.
SCR catalyst aged or contaminated
mediumA plausible cause — test and verify before replacing parts.
Related help
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