HPD Innovations – Refueling Safety Interlock System


Every year, as a result of human error or mechanical malfunction, there are instances of drivers leaving their pit boxes with the refueling hose attached to the car. All of these incidents create the potential for a fire in the pits and injuries to the driver, crew members, or others in the pit-lane area. It was just such an incident – one that resulted in serious injuries during an American Le Mans Series race in 2008 – that led to the development of this system. The system had been in development at HPD since 2009 for use in both the IZOD IndyCar Series and endurance sports-car racing and was introduced at St. Petersburg in 2011, when the series made it mandatory for all cars.

In May of 2011, HPD was awarded the 45th annual Louis Schwitzer Award for motorsports engineering innovation and excellence in recognition of the Honda Refueling Safety Interlock System.


The system is designed to reduce the potential for pit fires and injuries resulting from drivers leaving their pit boxes with refueling equipment still attached.


At the heart of the system is a fuel-probe electronic sensor, installed in the refueling "buckeye" – or inlet valve – on an IndyCar chassis. When the sensor detects a connection between the pit-lane refueling nozzle and the buckeye, software in the Engine Control Unit signals the Gearbox Control Unit to place, or hold, the transmission in ‘Neutral’, and prevents the driver from leaving the pit lane before the refueling hose is detached from the car.

Sequence of Operation

1. Car comes into pits and stops for refueling. Refueling nozzle is inserted.
2. Photoelectric sensor in fuel "buckeye" detects engagement of refueling nozzle.
3. Engine Control Unit (ECU) commands Gearbox Control Unit (GCU) to shift and hold transmission in neutral.
4. All paddle-shift requests are ignored during refueling.
5. Refueling is complete; nozzle is removed and no longer detected by the sensor.
6. Driver can now select first gear and leave the pits.


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