Outback Sport: Coolant Mystery Behind Check Engine Light

Had almost the same issue on my 2002 Impreza last summer. Have some experience with basic maintenance but leave major repairs to professionals. The check engine light combined with low coolant levels immediately points toward potential coolant leak issues. After topping up the coolant and checking for visible leaks, I noticed the problem kept returning. The engine was also running a bit hotter than usual. Took it to my regular workshop where they found a damaged wire connection to the coolant temperature sensor. The faulty connection was causing incorrect readings and triggering the check engine light. Total repair cost was 95€, which included diagnostic time and fixing the connection. But before jumping to conclusions, what engine size does your Outback Sport have? Also, have you noticed any: White exhaust smoke, Sweet smell from the engine bay, Visible coolant spots where you park, Air pockets in the cooling system These details would help determine if your issue matches what I experienced or if you might be dealing with something else. The symptoms you describe could point to various issues ranging from a simple sensor problem to more serious concerns like a head gasket failure. Would be good to pressure test the cooling system to rule out any actual coolant leaks, since constantly having to top up radiator fluid is never normal.

Thanks for the detailed suggestions. Following up on my issue, I checked the parking spot this morning and found small puddles of coolant. Did a closer inspection and noticed the upper radiator hoses are quite soft and worn. At 83819 KM, these could definitely be original parts showing their age. The engine temp has been running a bit higher than normal and the coolant reservoir level keeps dropping even after topping up. No white smoke or sweet smell so far, which is somewhat reassuring regarding the head gasket concern. Going to get the radiator hoses replaced first since they seem to be the obvious culprit for the coolant leak. Will report back on whether this resolves the check engine light and cooling issues.

Thanks for the update, sounds very similar to what happened with my Impreza. Those soft radiator hoses are definitely a telltale sign, mine lasted about the same mileage before needing replacement. The coolant leaks you described match exactly what I experienced before replacing my hoses. The constant need to refill the coolant reservoir and those small puddles are classic symptoms of deteriorating radiator hoses. Good call on planning to replace them, this should address your leak issues. When I had mine done, they replaced both upper and lower radiator hoses since they tend to wear at similar rates. Plus, the cooling fan and other components were easier to access while doing both. The lack of white smoke and sweet smell is encouraging. These were also absent in my case, which helped rule out head gasket problems. After my hose replacement, the engine temperature returned to normal and the check engine light cleared once the system was properly filled and bled. Just make sure they pressure test the entire cooling system after the repair to confirm there are no other leaks. My total repair cost including new hoses and coolant was around 180€.

Much appreciated for sharing your experience. I did a visual inspection again today and wanted to give an update. The water pump is actually showing signs of weeping around the bearing seal, which I initially missed. There are traces of dried coolant around that area too. Given this new finding, I will have both the radiator hoses and the water pump replaced since they are likely original parts. Makes sense to do both while the system is already drained. The radiator cap also looks pretty worn, so I will have that replaced too while everything is apart. The small puddles I noticed earlier are actually more concentrated around the water pump area now that I look more carefully. This explains why the coolant level keeps dropping even after refills. At least there are no air pockets or gurgling sounds that might indicate more serious issues. I will schedule the repair next week and update once everything is fixed. Thanks again for helping me diagnose this, having an idea of what to expect makes the whole process less stressful.