P0440 Gone but now P0133?

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
My 2003 fuel tank was replaced for free from the dealer under a leaking filler tank recall. I had the dreaded P0440 code. A month later I replaced the Fuel Pump with a Bosch unit which is stock. The P0440 never went away and I threw money at various Evp parts to no avail. Chevy wanted to charge me $80 to diagnose the issue I said hell no after they replaced my fuel tank. I chalked it up to the brain unit just giving a false reading as I replaced many parts , 02 sensors back and rear, ign coils, etc . Just did a oil change and fuel filter change and hadn't run the OBD Fusion app in a while and got the P0133 code?

Possible causes
  • Faulty Front Heated Oxygen Sensor Bank 1
  • Front Heated Oxygen Sensor Bank 1 harness is open or shorted
  • Front Heated Oxygen Sensor Bank 1 circuit poor electrical connection
  • Inappropriate fuel pressure
  • Faulty fuel injectors
  • Intake air leaks may be faulty
  • Exhaust gas leaks
MPG I will say is decent, but I did notice a sluggish feel a couple of times driving...what do you guys think?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
What brand O2 sensor did you use? If you didn't have this code with the old.one, have you tried putting the old.one back?

Is P0440 still active?
 

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
What brand O2 sensor did you use? If you didn't have this code with the old.one, have you tried putting the old.one back?

Is P0440 still active?

Ac Delcos most of the parts replaced where Ac Delco I believe the front one which is the putting of the P0133 is the updated version of the O2 sensor and its been almost a year since they got replaced. An no the P0440 is no longer showing on the OBD
 
Last edited:

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
If you still have it, I'd try the old one on the front. You should get voltage readings from it to see how it's working and getting readings. The new one might have died a premature death.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
You see the 5v going up and down on a graph, which shows it's working.
 

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
You see the 5v going up and down on a graph, which shows it's working.

So its running and working great the volts where going down and up to .25, .40, .62 and down and to .32, .26, .52 etc while I was driving to work this morning, downstream sensor seem to stay around .52 up to .72 and everything in between. I cleared the code and I know it will come back, I don't want to start chasing gremlins again
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
But is it a pretty steady up/down graph, almost like a heartbeat?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Yeah, your bank 1 sensor 1 doesn't look good. Should literally look like a heart beat. I'd change the front sensor. Sensor 2 looks fine. Unless it gives you an error code, you never bother with #2 as all it does is monitor the efficiency of the cat, which is why it's pretty steady.

This is what it should look like:
o2-normal.png
 

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
Interesting Those readings changed as driving back from work....The good about Amazon is the seller still gave me a one year warranty on the part so I am doing a return on it.
 
Last edited:

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
Well I changed out the front sensor today took about 5 minutes but left the battery disconnected for 30 minutes, not realizing I could have cleared out the code with the OBD :bonk:

So the bigger sensor I got last year was the updated version that was suggested on the board, as you can tell they look completely different.

Sensor1.jpg Sensor2.jpg


Sensor2.jpg
Reading1.PNG Reading2.PNG

Readings look more like a heartbeat now.......
 
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AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
I'm over at my parents house and wont be driving the Trailblazer back to Phoenix until Tuesday...I'm heading up to LA in a rental car...So I was checking which pulley was making the noise and now I am thinking its not the pulley. I could a hear a ticking sound on warm up and it goes away once the Trailblazer is warmed up. I think I heard from the board say that these engines tend to do this?

I just did a oil change about a month ago using Castrol High Mileage 10W-30 Full synthetic ...Yes I know its the wrong weight but in Az it doesn't matter and read up the thicker oil might be better since we have more heat. Could the thick oil also be a causing the tick?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
:popo: Going off-topic. I'd suggest starting another thread.
 

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
Well I guess its Monday and too good to be true, Ive had the stupid change oil warning on my vehicle for the past 2 weeks on. Ive been trying to reset it by turning in the ignition to the on position without turning on the engine and pushing down on the gas pedal... this morning I notice that the SES and the Oil change warning where the only ones that seem to be on. I wasn't able to reset the change oil warning When I saw this I knew that damn SES would come back on the dash, which it did when I was on the freeway to work. I'll be checking what the OBD says after work, but this is BS with this Trailblazer, so over this effin SES light being on even after buying a brand new O2 sensor.
 
Last edited:

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
For the oil change light, you have to press the pedal like 3 or 5 times.
 

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
The oil change warning is gone, was annoyed went outside to do it again, realized I had to let it pop up first before I started pushing down on the gas pedal, the lovely SES light is still there
 

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
Ok ran the OBD this morning while driving to work and the P0440 code popped up again, I am at my effin witts end with this code, Ive dumped money in parts that where fine and this code is still there....
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
I suggest reviving your P0440 code popped up again thread since THIS issue is actually resolved.

Gas Cap, Charcoal canister, Evp purge valves, Evp line to canister, new gas tank, new Bosch fuel filter, and other items replaced and this P0440 code was still there after al that money was thrown at good parts and no this was not resolved because the 02 sensor went bad and the P0440 code went away only to come back after the other code was fixed.
 

AzTruckGuy

Original poster
Member
Dec 1, 2015
501
scottsdale, az
Emailed Jeremy over at LimeTune, he will be getting rid of the stupid P0440 code, I ordered my tune today. Looking forward to seeing how the Trailblazer handles over the tune
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Well, that's one way of 'fixing' it.
 

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