mossy26

hi all
havin a annoyin prob with 94 import wrx,the temp guage needle is readin about 3/4 the on the dial when it should be in the middle,the coolant level is fine and there no issues with heatin/air con etc
however on checking the fault codes its comin up 21,24,33
could it be the iacv or maybe a coolant sensor issue?

any help much appreciated!

Glowplug

iTrader: (8)

Do a full ECU reset and if the same codes are showing change the sensors. 21 and 24 first and you might find 33 will then clear it self.

mossy26

had a feelin it would be somethin like that to do,ill try get it all done tomorrow,cheers.

Glowplug

iTrader: (8)

A faulty 24 IACS can cause the 33 VSS2 to show due to mis-information being sent to the ECU, ie it doesn't know when to idle and thinks it should be recieving a speed signal. And the 21 ECTS can/will cause issues, depending on whether it has failed open or closed.

mossy26

ahh thanks for that! well explained!
ive changed the coolant sensor,gonna reset the ecu 2moro n then see what happens?
found another iacv if its needed

Glowplug

iTrader: (8)

No problem mate.
Almost 100% sure you will need to change the IACV so don't be surprised if it flashes up tomorrow.

FB Tuning

iTrader: (30)

The early WRX's run 2 coolant temp sensors in the water cross pipe - A 2 pin, brown plug sensor signals to the ecu, and a single pin sensor for the instrument cluster gauge.

If you suspect a problem with the instrument gauge or sensor, remove the spade connector from the single pin sensor and ground the connector, turn the ignition on and check the needle moves to 'fully hot'. If it does, replace the sensor. If not, you have a problem with the wiring or gauge.

As above, also reset your ecu and recheck for codes, addressing them in the relevant order

mossy26

so fbtuning r u sayin u dont think its the idle air control valve then?

FB Tuning

iTrader: (30)

I'm not saying that at all - In your original post, you said you were also experiencing a problem with your temperature gauge needle, and i was just trying to explain some test steps for you to pinpoint that fault.

WRT the stored faults on the ecu (none of which would be related to a misreading instrument coolant temperature gauge), i would agree with the info b13bat is giving you - IACV will probably need to be replaced. Speed sensor fault normally only a genuine problem when the speedo doesn't work (part of the cable snapped), or faulty clocks.