[V6-12v] Temp. gage reading low, trouble code 2312

[Scott Thompson]

Tom,

I'd say it's very likely that it's the thermostat. This exact situation
happened on both my wifes and my Dad's 96 A4s.
The thermostat is not easy to get to.  You need to remove or at the least
wrestle with the timing belt (check the archive over the last month, there
were some posts on this).  I was able to buy a thermostat from a local parts
store, but once finding that I needed to fiddle with the timing belt, I just
had the TB and waterpump done too (It was due in 8k miles anyway), and
returned the thermostat.

-Scott



----- Original Message ----- 
From: "Tom Christiansen" <tomchr at ee.washington.edu>
To: "V6-12v List" <v6-12v at audifans.com>
Sent: Wednesday, January 14, 2004 3:20 PM
Subject: [V6-12v] Temp. gage reading low, trouble code 2312


> Folks,
>
> The temp gage in my 1994 90S reads very low. On short drives (<15 min)
> in the current 45-50 degree (F) weather the needle on the gage barely
> makes it up to the minimum mark. Even after riding in stop-and-go
> traffic for maybe 10-15 minutes followed by a short ride on the freeway
> it usually doesn't make it higher than slightly below the second fat
> mark at about 11 o'clock on the gage. On longer drives (one hour or so)
> on the freeway the gage typically sits around or slightly above the
> second small dot from the bottom. I have also been getting the 2312
> trouble code indicating trouble with the Engine Coolant Temperature
> sensor G62. I'm not 100% certain of the code number, but I am 110% sure
> it was the ECT error code. The heat comes on before the needle reaches
> the lower dot below the minimum mark on the gage.
>
> I changed the ECT sensor. The sensor which was in the car (suspected
> faulty) had an amber or brownish-orange 2-pin connector. The replacement
> had a white connector. Don't know if there is a difference between the
> two. I've thrown the old ECT away... While changing the thing, I cleaned
> the connector.
>
> I have paged through Bentley for procedures on how to test the ECT
> sensor and the gage. I remember testing the new ECT sensor before I
> installed it and it performed roughly like it should (the manual
> mentions approximate values of resistance vs temperature, but I didn't
> have a thermometer available to verify the ambient temp. I just
> guessed...).
>
> For testing the gage, Bentley recommends messing around with ECT thermal
> switch F76, which should be a 4-pin device located in the coolant line
> behind the passenger's side cylinder head. I remember looking for this
> without finding it at different time. Is Bentley on crack (wouldn't be
> the first time!!) or have I just not looked hard enough? The only other
> coolant temp. device I recall seeing is the huge thing in the bottom of
> the radiator controlling the fan.
>
> Any suggestions on how to drive this gremlin away? Is this an obvious
> case of stuck open thermostat? Or is it more likely to be an electrical
> issue?
>
> If it turns out to be a thermostat issue, I suppose I'll need a new
> thermostat and an o-ring (+ coolant). Are these dealer-only items or
> should I shop around a bit? Any advantage/disadvantage of a non-OEM
> thermostat?
>
>
> Thanks,
>
> Tom
>
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