Atmospheric Pressure Sensor Location?

[infiniongroup]

Hey guys, whats up?

I have a 92 N/A Legacy Automatic and have had an issue with it for about a year now, the car has been on the backburner so I am now just getting into fixing the issue. Anyways, the problem is last winter the car started to become hard starting when it was cold out and the engine was cold, giving it slight throttle was the only way to keep it running until it warmed up a little bit. Finally the CEL came on, a diagnostic test confirmed that the Atmospheric Pressure Sensor is throwing a code. The code was 45 I believe.

I have heard mixed things from mechanics locally, they all say the ECU has a APS built in, but I beg to differ, I'm assuming its somewhere under the hood.

So the question is, where is the APS located and does anybody have a photo of it.

Thanks in advance, any help is much appreciated.

I will have to post some pics of the old girl soon.

[glennda5id]

I think it is part of the ECU.

From the FSM:

DTC 45

A faulty atmospheric pressure sensor will set code 45 in the on-board diagnostic system. Because this sensor is an integral part of the ECU, it is necessary to replace the ECU if code 45 is displayed. In addition to the trouble code, a defective atmospheric pressure sensor can result in symptoms such as poor idle quality and failure of engine starting.

[Legacy777]

The atmospheric pressure sensor is definitely on the ECU.

Typically if you get a code like this it's erroneous. For cold starting issues, typically the problem is the coolant temp sensor. I'd suggest replacing it. It's only about $20 from one of the online subaru parts dealers.

[infiniongroup]

Thanks for the input guys. Its is MUCH appreciated!

Today I'll be checking locally to see if any of the parts stores have a coolant temp sensor in stock, if that does not cure the problem then its onto the ECU.

EDIT: The leggy is also getting new rear brake lines ran also, one of the steel lines decided to pop the other night, so no driving it until a new line is ran.

And regarding the ECU, do I have to get a direct replacement, meaning same year ecu? I understand that there are AT/MT Versions so i need to buy a AT version, but its a pain in the ass to find a 92 ECU locally, and ebay hasn't been of much help either.

Also going to be doing the Power mode modification to the ecu pin A4, going to install a switch somewhere (ridiculous labeling will follow, most likely Dynamic Engine Enhancement Mode, its nice to know people who have vinyl printers).

[Legacy777]

The 92-94 non-turbo ECU's should all be interchangable. Doesn't matter whether they are AT or MT.