# Putting AdBlue in the Diesel Tank: What Happens and What It Costs

> Putting AdBlue into the main diesel fuel tank — not the AdBlue reservoir — is a costly mistake that is becoming more common as more AdBlue-equipped vehicles enter the US fleet.

- Canonical URL: https://www.formancetane.com/news/adblue-in-diesel-tank-putting-adblue-wrong-place
- Published: 2025-11-12
- Author: Forman Cetane
- Publisher: Forman Cetane, a trade name of Forman Pacific, LLC

## The Rising Frequency of AdBlue Misfuels

As AdBlue (Diesel Exhaust Fluid) becomes standard on modern diesel vehicles in United States, a new category of misfuel is emerging: drivers filling the main diesel fuel tank with AdBlue, or filling the AdBlue reservoir with diesel. Both are damaging, but AdBlue in the diesel tank is the more serious scenario by a significant margin.

## What AdBlue Does to a Diesel Fuel System

AdBlue is a 32.5% solution of urea in deionised water. It is highly corrosive to metals used in diesel fuel system components — particularly the copper and aluminium alloys used in fuel pump internals and injector bodies. Within minutes of AdBlue contacting a diesel fuel system, corrosion begins. If the engine is started with AdBlue in the fuel tank, the high-pressure pump will begin to fail almost immediately, and the corrosive mixture will be circulated through every fuel system component.

## The Cost

AdBlue in the diesel tank almost always requires replacement of the fuel pump and injectors — the most expensive components in a modern diesel engine. Typical repair costs for this scenario in United States range from itemised charges on our rate card to significant cost depending on the vehicle. Do not start the engine. Call Forman Cetane on [(866) 777-3712](tel:18667773712) immediately.

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Source: https://www.formancetane.com/news/adblue-in-diesel-tank-putting-adblue-wrong-place