Hey everyone, I'm the proud owner of a 91 legacy wagon, non turbo, front wheel drive, automatic. I've got a persistent check engine light with a code for atmospheric pressure sensor. As I understand it, this sensor is part of the ecu... am I right? Anyway, if this is right, does anyone have a part number that I can use to search ebay? Or one to sell? Thanks.

Oh, and if you know what year cars will swap?

I've got a persistent check engine light with a code for atmospheric pressure sensor.

 

isn't this is a MAP sensor? not part of the ECU? so you do not need a computer.

 

90 - 94 should swap in no problem, i think. but i would check you wire connections and vac lines under the hood first. it could be a bad hose.

I beleive the MAP is actually part of the TCU's assortment of sensors and it's input is then also routed to the ECU..... the ECU itself has no MAP sensor that is external so if it's not the one on the passenger side strut tower then the ECU must have an internal MAP that is bad. Though I have never seen nor heard of this happening before.

 

GD

According to my Mitchell manual at work, there is no MAP... so I need the computer. Do you know any part numbers? When I search ebay for "91 subaru legacy ecu" I get listings for cars not necessarily legacies and years through the late 90's... I'm pretty sure these won't all work, right?

According to my Mitchell manual at work, there is no MAP... so I need the computer. Do you know any part numbers? When I search ebay for "91 subaru legacy ecu" I get listings for cars not necessarily legacies and years through the late 90's... I'm pretty sure these won't all work, right?

 

according to my 1990 FSM - this is a correct diagnosis.

 

"Trouble code 45: Atmospheric Pressure Sensor

 

When trouble code 45 appears on display, replace ECU"

 

I would think that any FWD automatic ECU from 90-94 should take care of it for you.

sorry i cant give you an exact part number, my car is an AWD...

Any 90 through 94 *Legacy* (Not Loyale's) ECU will work. AWD/FWD and automatic/manual don't matter. The ECU doesn't care about the former, and the latter is determined by a ground pin on the harness not by the ECU itself.

 

If it were me I would open the ECU up and see if it's just a bad trace or solder joint or obviously burnt transistor/cap. The Japanese solder tends to corrode and shrink over time and that is the biggest cause of electronics failure among Subaru's, Honda's and Toyota's. Mitsubishi just uses junk caps that leak and burst all over their boards..... lowest bidder components

 

GD

Edited July 26, 201114 yr by GeneralDisorder

item #1 in the drawing.

 

http://opposedforces.com/parts/legacy/us_b11/type_3/engine_electronic/relay_and_sensor_engine/

Cool... thanks for the responses everyone.

Hi,

Legacy Central has the ECU pinout HERE. It shows a "barometric pressure sensor" for the '90-92 models only.

 

As already noted, I'm 99% sure I read this is internal to the ECU...can't find it now.

 

The '92-94 ECUs should work, but I believe your '91 TCU may be looking for the ECU's sensor from the '90-91...not sure if it'll throw a code - flashing 'power' light'.

 

This POST has a link to pics of the FSM's TCU pinout w/the 'atmospheric sensor' in the TCU.

 

Td

Edited July 26, 201114 yr by wtdash