Code result
P20F6
Reductant Injection Valve Stuck Open
High severity
What it means
The DEF injection valve at bank 1 unit 1 does not close when commanded — DEF flows continuously into the SCR. Risk of crystallisation in the catalyst and over-dosing.
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
Valve seat eroded or contaminated
highOne of the most commonly reported causes for this code — check this first.
Valve plunger seized open
mediumA plausible cause — test and verify before replacing parts.
Carbon or debris buildup preventing free movement
lowLess common, but worth ruling out after the more likely causes.
Related help
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