check engine light

[Euphman06]

I know I have a 95 legacy L and this forum is for first generations, but I was just wondering if anyone could tell me why my check engine light came on. I dont know how to check for codes or whatever, can anyone tell me? but I looked under the hood and noticed that the engine coolant cap popped off, would this cause the check engine light to come on? I also think it could be the gas gauge, it isn't reading right anymore, I dont know if the check engine light would read that or not. I think the float needs to be cleaned but I dont know how to get to it, again can anyone tell me? THanks for your help, I think this is one of the most active subaru forums that I found.

[Legacy777]

I don't think the radiator cap being off would cause the CEL to come one...but anything's possible.

If you're car is OBD2, which I'm pretty sure it is. Take it to autozone or another local parts store. They can check the codes for you.

[IronMonkeyL255]

Wasn't it '96-on that were OBD-II?

[vrg3]

Nope; Legacies went OBD-II in 95.

The engine may have overheated... is it possible that an overheating engine throws a DTC?

[mgjs1]

Autozone reader can check our codes right? The port below the dash is the same as our 00 Honda Odyssey anyway.

My CEL is clicking on/off 3-4 times right after startup. Also, startup is getting more difficult and idling rougher right after startup (as smoke blows out tailpipe). Usually after parked facing downhill.

[professor]

>>engine coolant cap popped off

>>(as smoke blows out tailpipe).

Uh-oh. I don't like the sound of that. Is the smoke white (steam?)

if so you may have coolant draining into the cylinders while parked, which would cause overpressure of the cooling system (cap pops off), white clouds on start-up, and difficulty starting as water doesn't burn too well.

get the codes first but codes won't diagnose a blown head gasket, you'll have to do that by finding water in the oil, oil in the coolant, or intermittent overheating and coolant disappearing without an external leak

[Project_Legacy]

water in the oil, oil in the coolant, or intermittent overheating and coolant disappearing without an external leak

would ALL of these have to be present to diagnose a problem as a head gasket?

[professor]

No. you can just have slight loss of water, and some steam on start-up if you have a slight leak into the combustion chamber.

You can have some overheating with no other bad evidence if the leak is such that it only blows combustion gasses into the water jackets sometimes

usually they all end up the grand-mal symptoms of massive steam and bubbling in the cooling system, and overheating. the gas pressure in the cooling passages prevents the water from flowing around properly, so it overheats

it all depends upon where the gap is in the head gasket, and how big. A slight leak like the first example can go on for a long time, I hade one in my old BMW 3.0cs and used barr's Leaks sealer and drove it like that for several years, but if I let it sit for a few weeks, the cylinder would start to fill up with water sometimes, and I'd have to remove the plug to let the water out.

[mgjs1]

No overheating (since recent new water pump). No coolant disappearing. No overpressure or blown radiator cap. No water in oil. No oil in coolant.

Just hard to start, then rough idle for up to 1 min post-ignition. During the 1 min, there is smoke from the tailpipe, but I would not characterize as "white" or "steam," rather darker ... gray/blackish... less opaque and less "whitish" than classic burning oil (that used to blow out my tailpipe before I got some of my oil leaks fixed recently), although it smells like burning oil.

It is noticeably worse when parked facing downhill.

(Recent changes: New water pump, belts, seals. I accidentally let the power steering system get low on ATF this week... I smoked the belts a little and got some bearing grinding, but have refilled and now it appears to be working ok).

220k miles... might be time for a trade-in/up.

[mgjs1]

Any thoughts re my last post. I'm going to replace plugs and wires today, since that's easy and it needs it anyway. I'm not a car guy, but I'm trying, and could use some good ideas/guidance if it is possible based on the info in my last post. Thanks.

[Manarius]

Well, if it smells like oil, it probably is . You might have a little oil getting into the combustion chamber even though you got a lot of oil leaks fixed.

Might want to trade in if it annoys you enough lol.

[mgjs1]

Well, I read the codes (thanks for the excellent instructions at www.surrealmirage.com). On the standard diags, I read a 21 (water temp sensor), and in the "D-check" I came up clean (although it started flashing regularly before I got into 4th gear; the only event contrary to the instructions).

Ordered a temp sensor, pickup tomorrow. Plan to reset the ECU after that.

Keeping my fingers crossed that this'll fix her up. Thanks for the help.

[mgjs1]

Another victory for the coolant temp sensor. Solved my rough idle at startup just fine. ECU is reset and not getting any more codes just yet. Thanks.

I wonder, could i have saved the $40 that Autozone charged me by simply cleaning the old one? I didn't think of that until after I had it out and realilzed how corroded and crappy it looked.

[wsimpson86]

Mine is on all the time, but i say Fldkfas it i hate this car anyone with 400 dollars can take my car. It still runs good.

[Legacy777]

No, cleaning the coolant temp sensor wouldn't have helped.