There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
No, they can be replaced with the engine in the vehicle, but it is not an easy repair.
I was not aware that headgaskets were repairable. I have always replaced them with new gaskets. If you mean who replaces headgaskets, then that would be an engine mechanic.
First off you stop driving the vehicle immediately. Otherwise you will destroy the engine. If the repair shop is within a couple of miles from your home and the engine is not overheating drive it there for repair. If it is over a couple of miles have it towed. You will have to have the head/heads removed and the gaskets replaced. You may also have to have the head resurfaced or replaced. This is a major repair and is not cheap.
If it does it at a normal running temp have your Mass Air Flow Sensor checked
Subaru 2.5 liter engine has a problem with head gaskets. If you have not had your head gaskets replaced, that is the first thing I would suspect.
There are pages and pages of things that can cause a check engine light. You need to have it checked with a scantool. Then the code can be diagnosed and repaired.
You will need to strip down everything off the top of the engine to get to the head gaskets. A couple of tips on the job: Have the heads checked for cracks at a machine shop. When I did the job on my 93 Bonneville (same engine), both heads turned out to be cracked. I had a parts car with good heads thanksfully. Also, make sure all of the old gasket is scrapped off the surface of the block before the new gaskets are put on.
If the cork gaskets are not damaged then the engine block may be cracked. Check to see that the cork gaskets are indeed in place and not damaged.
did you check the radiator or the head gasket?
yes, but what kind of gaskets are you talking about?
Normally the answer is no. The only way the rings would need to be replaced is if the engine was worn severely or if you just kept driving it with the blown gasket and did serious internal damage. No way to know until it is opened up.
Have the fan motor checked to see if it's getting power. If not,then it will need to be replaced.