Need your guys' opinions.
 

Hi guys. First post her, I've been lurking and just gaining all kinds of useful knowledge from you guys.

I took my car to a shop today to get my tranny fluid and filter done. I had them do a test drive because of a hum I've been hearing for a little while, and the guy told me that it was most likely a wheel bearing. And thanks to your guys' useful info on how to tell if it is, I agreed with him.

So he changed my fluid and filter, and took a stethoscope and listened to my bearings. On the test drive we both figured it was the right front, by the way it sounded when taking turns, etc. But when he listened closely he suspects the left front more. I'm honestly not too worried about the bearing issue.

He also scanned the car for codes and these are the codes I have:

P0128 Coolant/thermostat
P0420 Cat EFF low bank 1
U1040 loss of ecbm, ebtcm communication
C1223 RF speed sensor open short

So, I already pretty much knew about all of these problems except the cat before hand, thanks your guys' knowledge and previous work done on the car.

What I need an opinion on is this. Here are two links for codes p0128 and p0420

http://www.obd-codes.com/p0128
http://www.obd-codes.com/p0420

Two of the symptoms match up for those codes. The Symptom being a faulty engine coolant temperature sensor.

Do you guys think this could be the cause for both of these codes?
Would it be an easy fix for me? I'm not a certified tech or anything, but I got a little common sense when it comes to cars.

The speed sensor and ECBM... I've read all through the stickied thread where one of your forum members tackles the good 'ole Trac off, abs off, and low trac lights. And he does point out the ECBM, so I should probably take a look at that. I had the tire off the other day, and I took a look at the connector going tot he hub, but I couldn't see any signs of damage, so i guess the ECBM is my best bet

Ummm, also, the code that says "Cat EFF low bank 1." What exactly does this mean in normal people terms? I get the feeling bank 1 means the oxygen sensor in front of the cat. But I'm not a trained technician, so I wouldn't know.

Thanks in advance for any info!

what is the motor...also are your cooling fans running properly

Ahhh yes. That's some info I forgot to give. I knew I was missing something.

It's the 3.4, the model is GLS.

The missing piece of info: The Cooling fans kick on shortly after I start the car, but it does it when the motor is cool. I knew it wasn't supposed to kick on that quickly, but i figured I wouldn't overheat, lol.

Also, lemme run out and snap a pic for you guys real quick on something else. It's some sensor I believe. It runs fromt he top of the intake after the box, back to the backside of the motor on top. And when it meets the motor, it has some play in it. I can move the tube, and the "Sensor" if that's what it is, moves with it.

i think u can just put a washer between ur cat sensor so it takes the part where it calculate out of ur exhaust ? ! i heard that before maybe ask if good thing


if ur fans never stop working they bipassed it strait to your ignition so when ur turn car on fans go on
i had that on an old alero one of my sensors was broken

same shits been happenin' to me man. Everytime i get to about 120-130 i can hear an odd, slight humming in my left, front wheel. I immediatley thought it was my bearing, took it into the shop to make sure and buddy said my bearings were fine. He said if it got worse to bring it in but since then, its got nohting but better, i can baarely hear the noise and it only starts when i hit about 125

well then i can't speak specifically for the 3400 because i have the ecotec however on my car it only took a couple minutes to change the sensor, and on the ecotec it is located on the back of the motor above the thermostat...i seem to remember people talking like the thermostat on the 3400 is back there so i would be willing to bet it is in that area...that particular sensor had to be bought at a dealership but only cost like $30...i would be willing to bet that it went out on whoever had the car before you so the fans quit working so instead of figuring out the actual problem they just bypassed the sensor

tru sayy

Click for vid. This is the thing I said I would take a pic of.


Not quite sure what it is


Ummmm, I don't think I'm willing to do that first part of your post. I'm not looking to make my own fixes, I'm looking to get it fixed to factory specs with as little money as possible, so rooting out the problem is the first step. Second is seeing if I can do it myself or if I have to bring it to a shop.

And I don't think the fans have been bypassed. This is an all stock car with 101K mi. on it. And the fans sometimes don't kick on until the normal operating temperature is met. So i know it's not bypassed. HOWEVER, every now and again, my temperature gauge in the cluster doesn't seem to want to work. So this in turn makes me think of my first post about the engine coolant temperature sensor.



.... KMPH right? Not MPH....

yes lol.....my bad

If the thermostat is on the back side of the motor... Then I think that is retarded. The engine bay is crammed enough as is, so putting a part that could easily be changed by a DIY guy in a tough to reach spot... That's just retarded.

the thermostat is under ur air intake ? no ? tright under the pic u showed us

The pic is actually a video, and I didn't really take a look. I'm sure i could locate the thermostat myself, but for once this month it's hot outside. I'm kinda trying to avoid it lol.

I mean, the thermostat should have a radiator hose running to it, right?

i cant confirm since i dont have my 3400 with me its stored for selling soon :) all i got is my 2.2 and im pretty sure that the plastic hose is a vacuum hose i replace one once because i was missing 50% of the hose it was just cut .. cost me 20$ ^^

I was pretty sure it was a vacuum hose as well. I know before all my dash lights decided to constantly stay on from the wheel speed sensor, every now and then the SES would come on by itself. So one day I ran up to Vatozone while it was on and had them plug up and lemme see. Scanner said I had a vacuum leak.

The thermostat isn't on the back of the 3400.... it's just under the TB which is on the driver's side of the motor. Best way to check if it's faulty is to remove it and throw it into boiling water and see if it opens up. It's not a sensor, it's strictly a mechanical device. I had mine go on me in the middle of the winter and it was stuck open so my engine coolant wouldn't get warm and I wouldn't get heat.

This video helped me:
http://www.youtube.com/watch?v=ZgLWR1dCXRM

theres no video. ;)

Fixed... Stupid thing wouldn't let me embed it.

there is no sensor its like a vaccum, its just a tube that runs from the intake to the back of the motor. mine has play in it too, if you move it around to much itll pop out the back of the motor, so make sure its in!

You are driving 120MPH???

Thanks for all the info and suggestions guys.

Shiwnath, great video, thanks for the link.

I'm leaning towards the ECT sensor right now since my temp guage wants to work at random. It's also on the symptoms list for both the P trouble codes, so i think I'll start with that.