how-fore's of the code 34

[rol1]

I have the "code 34" and was wondering how the code is detected as an error?

 

I can see that the computer could tell that the solinoid has been activated and closes the valve, (is the solinoid valve normally closed or open?) but how could the computer know if the egr valve is open or closed? There aren't any wires to the egr valve.

 

The solinoids in the pic-a-part lets me blow thru them, and the one on my 92 Loyale w/3sp-at flows free too. Does that mean that it is closed when power is applied? I have replaced it with a good clean looking one from the yard but I don't think the old one is bad.

 

Is a code 34 the egr valve remaining open? Is it plugged up? Built up so it can't close? I have pulled a few off the cars in the junkyard to look at and kept the clearest/cleanest one to trade with mine. Is this likely to fix the code 34? Is there more/anything else, to replace for this system/error other than the solinoid and the valve?

 

And higuys. I found this group looking for info on my new-to-me 92 Loyale. Now I have even more questions, too.

[hooziewhatsit]

The error referes to the solenoid, not the valve. It has no way of telling if the solenoid actually activated or not. To that end, some people have replaced the solenoid with a 50-100ohm 10W resistor just to make their CEL turn off.

 

The most common failure for the EGR solenoid is the connection inside the solenoid either shorts or breaks open. Therefore, when the computer tries to engage it, it does not get the desired response. To test this find an ohm-meter and measure the resistance between the two terminals. It should be around 35ish ohms.

 

The other not so common problems are either a break/short in the wiring harness to it, or a blown trace inside the computer.

[rol1]

So when the solinoid is bad the egr valve is open all the time?

[hooziewhatsit]

if, with no power applied, you can blow through the solenoid, then yes, I guess the valve would be open all the time.

[rol1]

if, with no power applied, you can blow through the solenoid, then yes, I guess the valve would be open all the time.

 

So how can replacing the egr valve have fixed the CEL as reported in other threads?

[stephenw22]

I don't know how replacing the EGR valve would do anything. The computer probably just looks at the current draw of the solenoid. The computer and EGR system isn't advanced enough to tell if the valve is screwed up. Maybe if the valve is stuck open, it can see an A/F ratio problem, and gives a 34, but I really don't know.

 

I'm one of the ones who used a 68 Ohm, 4W resistor to 'simulate' a solenoid. It cleared the code off my ECU, and the car seems to run just fine without it. I also plugged off the EGR system.

[rol1]

Cool, checked the solinoids I had and all but one were bad, and it was the one with broken plastic. Hit the Jyard after work and found 2 with 36.2 ohms.

 

No more code problems.

 

Thanks

[DaveT]

Cool, checked the solinoids I had and all but one were bad

 

This is the "normal" state of these solinoides...

 

*Every*single one I've had has failed. My solution is to go to the junkyard and find mid 80's Toyotas. They have a few each of a similar solinoide, and they are easily accessiblke to remove. Save the little "filter/caps" also. You have to figure out the airflow paths to make them work the same. Modify the mounting bracket a little. But they do not fail. Cut the Subaru connector off the dead one, solder it to the wires from the toyota one. Polarity doesn't matter.

 

Subaru units fail <5 years. Toyota units still in cars >10 years.

 

The EGR solinoid is off while the engine is warming up. At some engine temperature, the ECU turns it on. So it is on for most of the time the car is running. When it is on, the EGR valve can function. When it is off, the EGR valve is closed.

 

 

 

Dave