Edexcel appears to have dropped grade boundaries for its diploma in digital applications course after some schools and pupils struggled.
Pupils could pass by scoring just 60 out of 168 across four papers, which are each worth the equivalent of a full GCSE. The board had originally set the aggregate pass mark at 72.
The diploma has been marketed as a replacement for the general national vocational qualification (GNVQ) in information and communication technology, which was taken by 69,000 pupils this year, which will end next summer.
Edexcel's course is innovative and popular with many teachers. Pupils complete a series of projects on the computer, using spreadsheets, graphics packages and PowerPoint presentations. It is entirely coursework, marked internally by teachers and moderated by Edexcel.
Annual results for this year showed that 78 per cent of the 14,455 pupils who were entered for the main diploma module, worth one GCSE, passed it to achieve the equivalent of at least a C grade.
Twenty per cent gained a credit or better, 4 per cent a merit and 0.4 per cent a distinction.
However, The TES has discovered that the numbers achieving each grade below distinction would have been far lower if Edexcel had stuck to the original grade boundaries it had specified for the course. The final pass mark was set at 13 marks out of 42, even though diploma's specification said pupils would need 18 to pass.
For a credit, they needed 20, compared to the specification's figure of 24 and for a merit, 28 (30 in the specification). The distinction threshold was, as the specification promised, set at 36.
The three other papers also had lower pass marks than the specification stipulated.
Gary Clawson, chief executive of the Northwest Learning Grid, which has produced free resources to help schools teach the diploma and works with hundreds of teachers, said many had found it difficult to teach.
Some had got a rude shock after expecting to teach the full course in the same amount of time it took to teach the GNVQ. This counts as four GCSEs but often takes only one GCSE's curriculum time.
He added: "I'm not aware of any employer who allows their employees to get such a small percentage of their work right, and still emerge with credit, so there's work to go on this course."
An Edexcel spokeswoman said that the board had overestimated the amount of work expected of pupils, and that some staff had also "struggled" with it.
She added: "Scrutiny and evaluation of the pilot led the Qualifications and Curriculum Authority to agree on the removal of the pre-set grade boundaries to ensure parity with GCSE and GNVQ standards.
"The diploma courses are subjected to the same rigorous quality assurance procedures as all qualifications."