Hi have an Mahindra Scorpio 2.2, shows a steady check engine.

What is your question?

Performance reduces when drivenfor half an hour, fell the engine is overheating, gives a check engine light on AT. Feel gears are not shifting automatically. When engine is cool is back to normal. Service guys says it the issue of AT box and needs a replacement with ECM. Checked the mass flow good, oxygen sensors, hopefully it could be the catalac converter please help.

What makes this problem better or worse?

It's worse when the engine is hot

How long has your 2008 Hyundai Tucson had this problem?

Few months now.