P208E: Reductant Injection Valve Stuck Closed Bank 1 Unit 1
What to do
Ask whether the injector can be cleaned rather than replaced. The blockage is dried reductant, which dissolves in warm water, and on some vehicles a crystallised injector can be recovered — worth asking, because the part is expensive.
Ask why it crystallised. These injectors are cooled and the system normally purges fluid away from the tip after shutdown — if either has failed, a new injector will block again, so the underlying cause matters more than the part.
Mention if the reductant fluid has ever been topped up from an open or part-used container, since contaminated fluid accelerates this.
Do not leave it. With no reductant being injected the emissions system escalates towards a speed limit and eventually a vehicle that will not restart.
What this code means
The reductant injector is stuck closed and no fluid is reaching the exhaust.
Crystallisation is the reason, in the overwhelming majority of cases, and the mechanism is worth understanding because it explains the repair. The injector sprays reductant into a hot exhaust stream. When the engine stops, the tip stays hot and the fluid remaining in it dries — leaving hard urea deposits exactly where the needle has to move.
Every heat cycle adds a little more, until the needle no longer lifts.
Manufacturers fight this in two ways, and both matter to the diagnosis. The injector is cooled, usually by engine coolant circulating through its body; and the system purges fluid back after shutdown so nothing is left in the tip. A failure in either accelerates crystallisation dramatically — so a blocked coolant passage or a failed purge is often the real fault, and a replacement injector fitted without addressing it blocks again.
Ask whether cleaning is possible before replacement. Urea deposits dissolve in warm water, and on some vehicles a crystallised injector can genuinely be recovered — which is worth asking about, since these are not cheap.
The consequence is a system delivering no reductant at all, so nitrogen oxide output is uncontrolled and the inducement sequence begins. Expect it to escalate to a restart lockout if left.
Likely causes
Start here
- Crystallised reductant injector · moderate
- Faulty reductant injector · moderate
Less common
- Blocked reductant filter · moderate
- Reductant diluted or incorrect fluid · moderate
- Restricted reductant injector coolant passage · moderate
Symptoms
Components involved
Information, not instruction
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