EJ20G : I had a cel code 32 - oxygen sensor. Replaced it

 

Reconnected battery and turned key on, no more 32 BUT I have a code 21 now and the car runs worse than before. Code 21 is Coolant temp sensor. Why does it make this car run so crappy and where is it Under the mani or is it under the altenator?

 

And if it is bad can I snag one off a ej22? Or do I have to locate a jdm parts house?

Edited October 24, 201015 yr by mx4life

Yeah, you should be able to use the ej22 coolant temp sensor.

is it under the alternator or crosspipe? I found the temp sending unit under the alternator but not the sensor

I don't know specifics of the EJ20G, so the following is based on USDM EJs.

 

The sender near the alternator is for oil pressure.

 

The temperature sensors are on the coolant pipe. There are two -- the one with a single wire is for the gauge, the one that the ECU reads has two wires.

Yeah....it will be in the coolant crossover pipe. I've seen the temp senders in the front side of the coolant crossover and in the back on the EJ20's. So you'll have to look and see where it is.

Alrighty then. Off to search for it.

Got it changed. It was in the back.

 

Still have a problem though. Wont clear the 21 code (Coolant temp) runs super crappy rich at idle but above 3000 rpm it runs better. Im lost

help please??? I need the car to get to work.

If you replaced the sensor with a good one, then I would test the connections and the circuit itself for shorts or grounds. Was there any corrosion on the sensor connectors when you replaced it? You could even test the sensor you got just to make sure it works, then if it does work, then it is probably a short/ground somewhere in the circuit.

 

It runs crappy because the computer defaults to running the motor "choked" when it can't find the sensor I believe, so that's why it runs rich and like crap.

Ok, I will check things tomorrow. It was just weird to me that it came on right after I did my O2 sensor. And It wont clear. If all else fails I printed out the ECU pin layout and I can directly run fresh wire to the sensor to see if thats a fix. also code 49 is popping up and wont clear either. dont understand where these gremlins are coming from

Just curious, how long have you had the car? Could someone have swapped in the wrong ECU in the past? That's a reach I know but maybe worth checking.

Not to state the obvious or be too much of a smartarse, but usually when a code doesn't "clear" its because you haven't fix the problem

 

Here's a good link to Legacy777 site on the ECU:

 

http://www.surrealmirage.com/subaru/engine.html

 

Good stuff to know, and most likely applies to you, but I am not sure with the EJ20G, so keep that in mind.

 

Code 49 "Use of improper air flow sensor". Get the proper air flow sensor and that code will go away Again, see above.

 

Let us know what happens after testing all the stuff!

Just curious, how long have you had the car? Could someone have swapped in the wrong ECU in the past? That's a reach I know but maybe worth checking.

 

 

After some research, the stock ej22 turbo ECU works with this swap. I read that the JDM ECU is meant for 100 octane jap gas and there will be knocking and/or detonation .

Any links or ideas to testing my MAF? Ohms chart?

I wonder if you could have done something to disrupt the +5V supply the ECM sends out to all the sensors?

I'm not sure? That would mean to try a different ECU? Or .........?

ECU pin for the CTS had no continuity between it and the sensor. I made a new wire for it. 21 doesn't pop up any more but my car still wont start. How many volt/ohms does crank angle and cam angle sensor test at? Im trying to weed out any other possibilities

Edited October 24, 201015 yr by mx4life

Did you find the break in the CTS wire or just bypass it and run a new wire? The reason I'm asking is (for example) if the wiring harness got damaged somehow (got any squirrels or other rodenty type creatures nearby?) other wires in the harness may have also been damaged at the same point.

 

When you replaced the 02 sensor, did you use the kind you have to splice in or a plug in OEM part? I'm just wondering if you could have exchanged (for example) the +12V supply for the o2 sensor heater and a ground... created a short and taken out a fuse, the ECM etc.

 

Did you ever verify that the +5 v the ECM sends out to most of the sensors is present? If you've got the pinout for the ECM you should be able to find it. The MAP sensor gets this, the MAF sensor gets it, the TPS, etc. (Most of these sensors have +5, signal output and ground terminals on them.)

And when I say "ECM" I mean "ECU." I pretty much use them interchangeably to refer to the "engine control computer."

The O2the sensor I got was a common part number for this car. It's a 3 wire bosch I had to splice in. I'm sure the signal wire is correct but I was told the 2 heater wires polarity doesnt matter. I'm trying to find a wiring diagram so I can see what else in that circuit.

I'm going along with the O2 sensor wiring theory. Did you solder the wires together? If so, what type of solder did you use, and are you sure you didn't get any cold joints?

I'm going along with the O2 sensor wiring theory. Did you solder the wires together? If so, what type of solder did you use, and are you sure you didn't get any cold joints?

++

retrace your steps as this appears where you first went off track.

If I remember correctly, Bosch recommends you do NOT solder the wires since they are not copper. You use the connector they provide instead.

ya, I used the connector that was in the box. If someone thinks that the universal O2 sensor is wrong or have another idea let me know. Or I would like to find an O2 from another EJ that is OEM and not 200 bucks

You didn't cut the connector off the harness side did you? You can just unplug the O2 sensor and see if the problems go away. (other than getting an O2 sensor code)