Fuel Tank Sender Units: The Float and Resistance Track That Tells You How Much Fuel You Have

The fuel tank sender unit reports the fuel level to the dashboard gauge. A float on a swinging arm rides on the fuel surface; the arm rotates a wiper across a resistive track; the changing resistance becomes a signal to the dashboard. Simple in principle, but the resistive track wears (the wiper rubs across the same positions on most drives — most cars never fully empty their tank, so the high-fuel portion of the track is rarely used and the low-fuel portion wears first).

Symptoms

Gauge reading erratic or "stuck" at certain levels. Gauge dropping rapidly to empty when actually full. Low-fuel warning light staying on when tank is half-full. Speedometer and other dashboard signals may also be affected if the wiring loom inside the tank is involved.

Replacement

The sender is usually built into the in-tank fuel pump module — meaning replacement is the pump module rather than a separate sender. Access via the hatch under the rear seat or boot floor. Replace the gasket on refitting.

Brand

VDO, Bosch, Pierburg, Hella cover OE applications. The combined pump/sender module is the typical aftermarket part.

Find fuel tank sender units for your car on the Fuel Tank Sender Units collection.