P207F: Reductant Quality Performance
What to do
Be honest about where the reductant fluid came from. This code means the fluid itself has been measured and found wrong — diluted, contaminated, or not reductant at all — and the fastest route to a cheap fix is saying what went in.
If water or screenwash has gone into the reductant tank, say so immediately. It is a common mistake, it is fixable, and hiding it only means paying for diagnosis that arrives at the same answer.
Expect the tank to be drained and refilled. That is normal for this fault rather than being oversold.
Buy reductant in sealed containers and check the date. It has a genuine shelf life and degrades in heat and sunlight — a part-used drum that has stood through a summer can be out of specification, which catches out anyone buying in bulk.
What this code means
The reductant fluid in the tank is not of the required quality.
This is the verdict its circuit sibling is not. The sensor is working, it has measured the fluid, and the fluid is wrong — too weak, contaminated, or not reductant at all.
The usual explanations, and they are worth being honest about with a garage:
- Diluted with water. Either deliberately, to stretch it, or by topping up from a container that had water in it. The system detects this easily, because concentration is exactly what it measures.
- The wrong liquid entirely. Screenwash is the classic — the filler necks are deliberately different sizes and it still happens.
- Fluid that has aged. Reductant degrades in heat and sunlight and has a real shelf life. A drum that has stood in a yard through a summer may genuinely be out of specification, which catches out fleets buying in bulk more than private owners.
- Contamination from the tank itself, where crystallised deposits have redissolved into fresh fluid.
The repair is a drain and refill with fluid from a sealed container meeting the ISO specification — and it is worth doing promptly, because dosing weak fluid at maximum rate leaves deposits that crystallise the injector shut.
Do not treat this as a sensor fault to be cleared. The system will keep escalating until the fluid is right, ending in a vehicle that will not restart.
Likely causes
Start here
Less common
- Reductant fluid past its shelf life · easy
- Faulty reductant quality sensor · moderate
- Crystallised reductant deposits · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
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.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
Sign in or create an account to add what you found about P207F.