I just replaced the O2 sensor in my 90 legacy wagon and it is running pretty good but now it is giving me the 42 code. WTF! What is it and what does it do? How do I fix it? What will it do or not do untill I can fix it?

 

Thanks everyone for looking. I appreciate everyones input. Even if it is to say I am SOL!

 

What does the Subaru God (Josh) have to say?

somebody....anybody. Come on all you subasmarties...

42: Idle switch, Abnormal voltage input entered from idle switch.

Fail safe is to Judge OFF operation.

 

That is from Legacy777's page, BTW. . .

 

From that I would guess that you have a bad idle switch. Is the car idling badly?

I know what the code was for...

 

Car idles a tad rough but when it warms up it is fine. Should I replace it or skip it?

 

Is there anything besides the O2 sensor that would make it run rich? Still kinda stinky.

I'd clear the code first, and then see if it returns. If it does, then replace the switch. I dunno the cost of the switch though. . .

Here's my yet-to-fail fix for that code.

 

Swap throttle bodies. Pull one from a junkyard. I have swapped throttle bodies on my car to have one that still has its factory settings (I played with stopscrews when I was younger :-\ ). Then I did the same with a coworker's 92 Legacy who had the same code. Problem fixed.

 

The idle switch is built into the TPS, which is on the passenger side of the throttle body. The TPS is set from the factory in a certain position, you can see the white marks on the screws. It's best not to mess with that, so if you just swap the whole thing, you won't have that problem.

Thanks for the tip. I try to find a legy with low miles so I can pull the TB..maybe I will take the entire engine and tranny. My tranny is sucking...

 

Thanks guys. I knew I could count on you. See you in Jan.

Test the idle switch in the TPS.

 

Follow this procedure

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing3.jpg

 

Here's the preceeding info, which tells you which pins are which

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing1.jpg

http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/TPS_testing2.jpg

 

If it's out of spec, adjust it so the readings are in spec, clear the codes, and see if you still get the code.

Even if those tests check out, you still might try subyluvr2212's suggestion. In my experience, the idle switch code is sometimes thrown when there's an inappropriate load on the TPS power supply, and that can be caused by something weird in the TPS.

Thanks Josh for the info. I think I am going to just replace the throttle. Maybe someone makes a bigger throttle body????

 

Anybody have any suggestions as to where I can find a bigger throttle body? Perhaps the WRX has a biggger one?

 

Hmmmm...

If you want a bigger TB....bore it.....the newer ones aren't any bigger and won't work with your car. However I wouldn't bother boring it.....it's one of the last bottlenecks.

How bore'ing...LOL. I wonder if it hasbeen done?