O2 sensor error

mbalbritton

mbalbritton

#@$%!
Joined
Mar 22, 2005
Location
Lakeland, FL
About 5-6 months ago I had a check engine light come on. Took it to the store to have them scan it. Came back with an O2 sensor error.

Went ahead and ordered all 4 O2 sensors from RockAuto. By the time they came in, the engine light had gone off. So, I stuck the sensors on the shelf and waited.

FFWD to the other day and the light is on again. I ordered one of those Bluetooth OBD2 scanners and it’s reading the following:
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It’s all bank 1 sensor 1.

What’s the chances I have a bad new sensor? What’s the chances it’s something else?
 
What vehicle are we dealing with here? What brand of replacement O2 sensors did you get?
 
Oh ya…

2014 GMC Sierra 5.3

I’ll have to go back and see if the O2 brand is in my RockAuto history.

EDIT: Went back and found that I ordered them from Amazon. Reluctantly admit that it looks like I ordered some China brand.

Might be worth looking at replacing bank 1 sensor 1 with a better brand and see what happens.
 
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What @Croatan_Kid said. O2 sensors are one of those where the parts house just doesn’t cut it and you don’t get to skimp. Chased my ass for a long time and fires the parts cannon at a Jeep once. OEM O2 sensor and magically all my problems were solved.
 
I usually go for Denso or NTK when it comes to O2 sensors. They make a lot of factory ones anyway. It's possible the ones you got aren't up to snuff, but make sure every fuses in that thing is good. Idk if they still do it, but in days past, the O2 sensor heater ciruit drew power through the same circuitry as other, completely unrelated stuff. As did the power for the OBDII port, which was usually the 12v outlet.

Looks like the upstream/sensor 1 sensors are the same left to right. Same for downstream/sensor 2.

Denso brand are 40 bucks a piece for the upstream ones on RockAuto 👌

With the code going from low voltage to high voltage on the heater circuit, it sorta makes me lean towards that sensor itself having a bad heating element.
 
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Croatan_Kid said:
I usually go for Denso or NTK when it comes to O2 sensors. They make a lot of factory ones anyway. It's possible the ones you got aren't up to snuff, but make sure every fuses in that thing is good. Idk if they still do it, but in days past, the O2 sensor heater ciruit drew power through the same circuitry as other, completely unrelated stuff. As did the power for the OBDII port, which was usually the 12v outlet.

Looks like the upstream/sensor 1 sensors are the same left to right. Same for downstream/sensor 2.

Denso brand are 40 bucks a piece for the upstream ones on RockAuto 👌

With the code going from low voltage to high voltage on the heater circuit, it sorta makes me lean towards that sensor itself having a bad heating element.
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Checked all fuses on all three panels. Under hood, and on end of dash in door jam on both sides. I only know of those three, if there’s more. All fuses gave me a continuity beep or passed visual inspection. Guess it’s O2 replacement time.
 
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You can download Torque app and use with the BT dongle. It an chart the 02 voltage. Once the engine has run a while, if you see a change in the O2 output, the heater is likely bad, as @Croatan_Kid mentioned.
 
ordered 4 new Denso sensors from Rock Auto. Swapped them out. Cleared everything with the scanner and took it for a ride. Maybe it was my imagination, but it seems to idle smoother. I had noticed recently a little rougher idle than normal, but felt good today.

Driving normal and watching the Scanner O2 readings for voltage and mixture (or whatever it was, not that I know what those numbers should be) They were at least registering and both banks reading the same. I got on the throttle pretty hard, and just like magic that stupid engine shaped light on the cluster illuminated. MOTHER $#%#$@%!!!

Ran a scan and got the same O2 sensor codes as previous, but also got a new one: P0420 Catalyst system.

Truck has 175K on it, just FYI. It's been a great truck. Only ever had to replace both AC lines and a temp sensor. excluding battery, tires, filters and brakes of course.
 
And it’s back like a bad case of crabs… or so I’ve heard.

Now that im spending some time to understand the numbers and readings… looks like the down stream sensors aren’t reading short term fuel trim. Might be the cheapy reader I have. I watched while driving around and they never registered at all.
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Sounds like the cats could be due for replacement.

Provided there's no issues with any injectors, fuel pressure, or intake gaskets...that may be the culprit.
 
doing some reading around online, Fuel filter could be an issue, which reminded me of a fuel tank pressure switch that I replaced 5-6 months ago.

I've never replaced the injectors. or had any work done on the engine. I certainly hope it's not the cats. Odd that it started as all bank one and now after swapping sensors, its both banks and the Cat system errors for both banks. I'm inclined to replace the filter to start with. far cheaper than cats and hasn't ever been replaced that I know of, so it couldn't hurt. REALLY don't want it to be the cats!!
 
mbalbritton said:
doing some reading around online, Fuel filter could be an issue, which reminded me of a fuel tank pressure switch that I replaced 5-6 months ago.

I've never replaced the injectors. or had any work done on the engine. I certainly hope it's not the cats. Odd that it started as all bank one and now after swapping sensors, its both banks and the Cat system errors for both banks. I'm inclined to replace the filter to start with. far cheaper than cats and hasn't ever been replaced that I know of, so it couldn't hurt. REALLY don't want it to be the cats!!
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COOL! I found the Fuel Filter right between the Blinker Fluid and Muffler Bearings. Apparently there is NO fucking serviceable Fuel filter on this truck.

If it is the Cats, Guess I need to figure out WHY.

please don't be the cats...

This modern computerised bullshit is annoying.
 
Yep...the last GM, half ton trucks with external fuel filters were the 99-02s. In 2003, they ditched the fuel filters AND cabin air filters. Terrible ideas...

Anyway, I'm leaning towards the cats at this point. If they're shot, it's either from a lean or rich condition that either cooked the inside or washed them out.

With all that said, I'd definitely confirm before replacing the cats. I'm not super familiar with the newer trucks with direct injection. I do, at least, know that low fuel pressure can cause spray pattern issues (as could partially stopped up injectors) and the AFM/DOD can have issues that would throw raw fuel in the exhaust.

I'd guess further diagnostic work would be in order!

It also wouldn't hurt to put some miles on it and *clean* the exhaust out. By that, I mean with the skinny pedal :D

Edit: Also...if you haven't done them lately...plugs and wires! Start simple.
 
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mbalbritton said:
COOL! I found the Fuel Filter right between the Blinker Fluid and Muffler Bearings. Apparently there is NO fucking serviceable Fuel filter on this truck.

If it is the Cats, Guess I need to figure out WHY.

please don't be the cats...

This modern computerised bullshit is annoying.
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Pm me the tag number and codes. I will send you oem testing
 
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