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Old 05-17-2007, 10:44 PM   #1
RS2001
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Default P0483 Cooling Fan Rationality Check Malfunction

What the hell is this? I have a 2001 RS (as made obvious by my name) with 95000 miles on it and it just threw this code. My cooling fan seems to be working fine, so I can't really imagine what the problem is? As luck would have it, I need to get my car smogged too, so I need this fixed a.s.a.p. Is anyone familiar with this?

-Dan
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Old 05-17-2007, 11:40 PM   #2
nast
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Someone correct me if I'm wrong... but I think it is when the coolant fan circuit is on for a certain amount of time but the water temperature doesn't decrease a reasonable amount. Possibly because of insufficient coolant or coolant flow, busted radiator fan, poor air flow....

I may be thinking of a different code...

If you aren't having any overheating issues maybe the code is just a fluke occurrence. Check your coolant level and clear the code... maybe it won't come back.
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Old 05-18-2007, 12:11 AM   #3
Jon [in CT]
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I think this code is set when the Engine Coolant Temperature (ECT) sensor signal fails to rise above 15 mV (~1°F) after 2.5 minutes of operation.

You probably need a new ECT sensor.
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Old 05-22-2007, 04:23 PM   #4
RS2001
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I'll check the coolant level this afternoon.
New ECT sensor? Great, how much is the dealer gonna rape me for that?

-Dan
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Old 07-14-2007, 03:48 AM   #5
ejicon
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I'm pretty sure I'm going to need one myself:
http://www.auto-parts-wholesale.com/...EmbWRpZD0xMTMx

I just don't know where the hell this part is located.. Can anyone help?
-Ellz
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Old 09-10-2009, 07:25 PM   #6
sick1.8t
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i know this is an old thread but just for anyone else looking, the coolant sensor (ect) is on the coolant crosspipe under the intake manifold. have fun getting at it. its got a one wire connector i believe.

i've also read this could be because of a clogged or poor flowing radiator or a bad thermostat not allowing the coolant to move around and cool enough.
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Old 09-10-2009, 10:29 PM   #7
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good to know
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Old 05-04-2017, 03:42 PM   #8
Rippey574
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Hate to dig up an old post, but new register and cant make a new one yet..

So I have the same error as the OP, I am trying to determine what is the actual cause. I have had this cel twice now about month apart.

I know the fans works, both at temperature and in diagnostics mode.
I do not over heat, gauge reading appears to be well regulated and does not go out of the inner nominal range marks.

Here is the oddity of it; with romraider when I monitor the temperature it shows a constant 0*. But the dash appears to be correctly registering. It will starts off scale and rises up like normal. So I am thinking this is a failsafe value the ecu uses for what ever reason since the dash appears to be working correctly.

Coolant was changed last year, flow appears to be good and dash produces heat.

I have rewrote the limit ranges for the fan controller, but have not had an issue and was done last year around the dog days of summer.

I am up for suggestions on what else to check.
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Old 05-05-2017, 10:40 AM   #9
Charlie-III
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Quote:
Originally Posted by Rippey574 View Post
Hate to dig up an old post, but new register and cant make a new one yet..

So I have the same error as the OP, I am trying to determine what is the actual cause. I have had this cel twice now about month apart.

I know the fans works, both at temperature and in diagnostics mode.
I do not over heat, gauge reading appears to be well regulated and does not go out of the inner nominal range marks.

Here is the oddity of it; with romraider when I monitor the temperature it shows a constant 0*. But the dash appears to be correctly registering. It will starts off scale and rises up like normal. So I am thinking this is a failsafe value the ecu uses for what ever reason since the dash appears to be working correctly.

Coolant was changed last year, flow appears to be good and dash produces heat.

I have rewrote the limit ranges for the fan controller, but have not had an issue and was done last year around the dog days of summer.

I am up for suggestions on what else to check.
IIRC, there are 2 ECT sensors for all years and engines, one for the gauge, one for the ECU. Sounds like the ECU ECT sensor failed/is failing. Both are on the crossover pipe, PITA to get to.

What year and model is your car, how many miles on it?
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Old 05-05-2017, 06:30 PM   #10
Charlie-III
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Old 05-06-2017, 04:46 AM   #11
CosmoTheCat
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Oooold cars had two.

Newer ones only have 1. For a while they were 3 wire setups, and then they went to a single temp sender that talks to the ECU which then talks to the cluster.

In 05, it'll be a 3 wire sensor on the front side of the water pipe, behind the alternator tensioner bracket.
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Old 05-06-2017, 09:08 AM   #12
Rippey574
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Thank you for the replies. It is a 2005 Impreza RS. Approx 112k miles. So the single 3 wire sensor will house both temp sensors correct?

And that location sounds like a joy to get to yay.
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Old 05-07-2017, 10:05 PM   #13
CosmoTheCat
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Correct. It's actually easier to get to than the back side. Pull the alternator out and it's right there.
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Old 05-08-2017, 08:41 AM   #14
Rippey574
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Thank you for the help. I will pull it and change it out.
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