The DTM allowed teams to make changes to the series' standardised steering-column system at Zolder because vibrations caused by the new breed of Class One engines have impacted reliability.
Several retirements at both Hockenheim and Zolder were related to standardised parts breaking due to the higher frequency with which the two-litre turbocharged in-line engines vibrate compared to the previous naturally-aspirated V8s.
As the engine is fitted to the monocoque chassis, the vibrations were able to cause damage in areas including the steering column.
An ITR spokesperson told Autosport: "For this weekend in Zolder, the steering system, which remains a DTM control part, was temporarily freed up for adaptation by the manufacturers, and a technical update [was] published by the DMSB [the German Motor Sport Federation].
"Now, if necessary, the manufacturers have a free choice of material for the casing and mounting.
"The background to this decision follows reports of occasional damage to the casing during the Hockenheim weekend, which probably resulted from vibrations relating to the way in which it was mounted.
"Given the limited amount of time between Hockenheim and Zolder, the manufacturers concerned were given the option to reinforce the casing on an individual basis following the freeing-up of the component."
Autosport understands that the issue was related to fabrication and parts carried over from 2018, with support from Japan's Super GT series - which also uses the Class One engine design - helping to improve reliability.
Several within the paddock said the stability of the long-running V8 era meant there was a perception that reliability appeared significantly worse than it actually was.
Asked by Autosport about the new engines causing reliability problems, DTM boss Gerhard Berger said it was "just early things. Less than I thought".
He added: "I think it takes two or three races and then it will be under control."
One driver said a consequence of the Class One engine was that although it is more efficient, it is having a knock-on effect on the reliability of cars.
He said: "There's a lot of spec parts built for cost, not performance gains. Clearly, they're weaker in a certain way, but they're [DTM] reacting and getting it together in the right way.
"I just think it's more expensive than people expected because you're having to replace things differently.
"You're not only dealing with vibrations, but you're also dealing with more heat, more issues all the way through."
Bart Mampaey, the boss of BMW Team RBM, said the Class One engine has "been a tremendous challenge".
Speaking before the start of the Zolder weekend, Audi motorsport boss Dieter Gass said: "We [the DTM] have come out of a period with known technology, known engines and reliability seemed to be granted.
"Now it's all new, the surroundings too, and it's not so straightforward now. I think we need to get used to it.
"I do think there will be more [reliability] points to be sorted."