Drivers are permitted to use four engines across a season, and face grid drops for exceeding that pool.
Now, two drivers have again been punished for taking new engines, having faced the same fate earlier in the season at the Detroit Grand Prix.
Two drivers penalised for engine number breaches
Graham Rahal and Kyffin Simpson will both start nine places back from their qualifying positions for the Saturday evening Iowa race after exceeding the number of engines permitted to be used across a season.
On road courses, the punishment is six places, but this is upped to nine for the shorter, faster oval tracks.
The Rahal Letterman Lanigan and Chip Ganassi Racing drivers have both fitted new Honda power units since the Mid-Ohio race.
#INDYCAR officials have announced a nine-position starting grid penalty for the following entries for unapproved engine changes: ⁰⁰➖ No. 4 Chip Ganassi Racing⁰➖ No. 15 Rahal Letterman Lanigan Racing pic.twitter.com/RyOzLop54M
It is a continuation of the issues which plagued the Japanese manufacturer earlier in the year, which saw customers use up engines earlier than anticipated.
Qualifying for the first event of the 2024 Hy-Vee IndyCar Race Weekend begins at 2.45pm (CDT), with race one getting underway at 7pm (CDT, Saturday, 13 July).