The DJ was hit by a lorry while riding his moped on Ibiza's busiest motorway, sending him off the road and into a shallow ditch.
Crane suffered concussion and had a deep gash on his left thigh. He was checked over at Can Misses Hospital and ordered to cancel all forthcoming work commitments, The Mirror reports.
Harding is currently in rehab to deal with depression and alcohol addiction. It follows the couple's decision to take a "break".
A source said: "Tom was so preoccupied with thoughts of Sarah, he wasn't really concentrating on the road. He came off the bike and was thrown flat on to the ground. He eventually pulled himself up and tried to clamber back on before passers-by advised him to get checked over at hospital.
"Tom was badly shaken, and has been left with grazes on his hands, some severe bruising and a gashed leg. But he was more concerned about the prospect of missing the radio show he was due to co-host. He immediately called Sarah and told her about the accident.
"She was in floods of tears and desperate to be by his side. If there's anything positive to have come from this crash, it's that the accident has confirmed for both Tom and Sarah just how much they love each other."
The crash happened on a stretch of motorway dubbed "Ibiza death road". Medics said Crane's helmet saved his life.
Earlier this month, Crane was said to be preparing to return to the UK from Ibiza for crisis talks with Harding.