Title says it all, for the most part. I'm three hours away, visiting family, and I get call from the wife stating her 2000 OBW threw a CEL. I suggested she drive by Advance Autoparts and have them read the CEL. She called back, stating the code was P1490. AA said it was a manufacturer specific code, and that she needs to contact a Subaru dealership for it.

 

Now, I really don't want to have Subaru charge me for pulling the code :-\... but a search for 1490 on the boards doesn't yield anything. The closest I could find on Google was "Low Speed Fan CTRL Relay Circuit", but the list mentioning the code wasn't specifically labeled for any manufacturer, much less Subaru. Several Subaru specific lists did not mention 1490.

 

Can anyone confirm what the code refers to? I'll be back in town tomorrow, where I can clear the code and watch for anything else popping up, but I'd rather know what's going on before I clear it. Or I'll just suck it up and take it into the dealership to have the code read, per recommendation here.

 

Thanks in advance! :cool:

Hi. I have an '00obw too.

 

DTC P1490 - THERMOSTAT MALFUNCTION Thermostat stuck open

 

Now this may seem odd, but the first question the procedure asks is....

Has engine operated at idle or has vehicle been driven with part of engine submerged under water?

 

Are there any other codes present as well?

 

Check radiator fan circuit. Does radiator fan continuously rotate for more than 3 minutes during idling? If yes, repair raidator fan circuit.

 

If no, replace thermostat. Highly suggest new OEM thermostat and new gasket and new coolant - use Subaru OEM coolant or flush several times first with distilled water before switching to something else such as Zerex G-05.

 

edit: don't forget the coolant conditioner/stop leak/holts radweld

Interesting code! If the thermostat is stuck open, then the engine won't reach full operating temperature. What is the temp guage on the dash doing?

I called the wife last night, and asked her to keep an eye on the temp. gauge on her way around errands this morning, specifically paying attention to how quickly it warms up. She said something to the effect that the car warmed up normally on the way over to Advance Autoparts *shrug*.

 

Troubleshooting from three hours away is not fun. As long as it's not going to develop into something serious (CEL probably won't, but with my luck...), I'll wait 'til I get back home to worry about it.

 

Thanks!

There may be another possibility. I'm guessing the ECU is determining the thermostat is stuck open based on the reading from the engine coolant temp sensor (ECTS). So if the ECTS is giving a low reading I'm guessing it could cause this code, though the service manual did not say anything about it.

 

If you have or could borrow a scangauge or something similar you could read what the vehicle thinks the engine coolant temp is; if it is staying below 180 deg F that would indicate an issue.

 

The temp gauge might not really show much in this case. The temp gauges are kind of weird. It seems from like maybe 150-190 deg. F the needle doesn't really move a whole lot. I've heard that's so customers don't think something is wrong because the needle moves around.

 

I don't think it's too much of an issue to drive like this for a while. There are a few risks, like if for any reason the engine is running rich because of this condition it could cause cat issues. Also you may want to do an oil change because the engine oil may not be getting up to temp then either thus letting condesnation and fuel build up in the oil.