Cause
Reductant tank empty or incorrectly filled
The diesel exhaust fluid tank run dry, or filled with something that is not DEF. It is distinct from dilution: this is an absence or a substitution rather than a weakened solution, and it reaches the inducement stages faster because the system can detect it immediately from level and quality sensing.
Diesel put into the DEF tank is the expensive version of this mistake — the filler necks are deliberately different sizes to prevent it, and it still happens. Do not run the engine if the wrong fluid has gone in; the pump and injector are damaged by circulating it, so a drain before starting is far cheaper than a system replacement afterwards.
A tank allowed to run empty is usually a warning ignored rather than a surprise, since the vehicle counts down in miles for a long way first. Refilling clears the countdown, but on many vehicles the system needs a drive cycle to verify itself before the restart lockout lifts, so a refill in a car park does not always start the engine straight away.
Typically an easy fix. Often worth checking before paying anyone to look.
Some of these codes mean you should stop driving
1 of the 9 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (9)
Codes where this is a likely explanation first, rather than merely a possible one.
- P203F Reductant Level Too Low Likely for this code High
- P207F Reductant Quality Performance Likely for this code High
- P2201 NOx Sensor Circuit Range/Performance Bank 1 Sensor 1 Likely for this code High
- P2214 NOx Sensor Circuit Range/Performance Bank 2 Likely for this code High
- P241D SCR Inducement - Forced Engine Shutdown Likely for this code Stop driving Critical
- P2BA7 NOx Exceedence - Empty Reagent Tank Likely for this code High
- P2BAF NOx System Driver Inducement Active Likely for this code High
- P218F Reductant No Flow Detected High
- P2BA9 NOx Exceedence - Insufficient Reagent Quality High
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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