Water in Fuel Sensor

A pair of contacts in the bottom of the diesel filter housing or water trap, detecting water by its conductivity — diesel does not conduct and water does. It exists because diesel fuel is the only lubricant a high-pressure injection pump gets, so water reaching the pump causes rapid wear whose metallic debris then travels downstream into the injectors. That makes this one of the few warnings on a vehicle where the remedy is free and immediate — draining the trap — and the cost of postponing it is most of the fuel system.

Also known as: wif sensor, water in diesel sensor, fuel water sensor, water detection sensor, water trap sensor

Referenced by 6 codes

WhatsApp Telegram X Email

Codes involving this component (6)

Other components in Fuel Delivery

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.

Working on this component

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.