Persistant Engine Light

[Pacheco_450r]

So I have 106k miles on my 2005 silverado. When I get into it a little to get on the freeway I'll get an engine light that comes on and stays for a day or so and shuts off. After this had gone on for about a month I borrowed a code scanner from a friend and the code came up saying it was the Bank 1 Sensor 1 having low voltage. I looked it up to find that is the driver side front o2 sensor. So I made sure I got the correct upstream sensor for my truck changed out the old one and made sure the fuse was good that goes to the sensor. Now two weeks later I'm getting an engine light again and its coming up as the same code. Any ideas what the issue is?

[CJM]

You need a scanner that can read it in real time to determine exactly whats going on. Also some of the cheaper scanners dont interpret the codes right too.

As for the sensor itself, did you reset the battery after you did it? Could also be a faulty or wrong sensor.

[chucked]

Its either running rich or still a o2s problem. What brand sensor did you buy? Could be the pcm, temp sensor, maf sensor, map sensor, high fuel pressure, clogged air filter, or a wiring problem.

[Pacheco_450r]

The battery has been reset, i guess there is a possibility the the o2 sensor is bad but unlikely?

The brand of sensor I got was Bosch. I made sure that it was the correct sensor for both my model and motor as well as the position (upstream). The air filter is clean as well as the mass air flow sensor. I guess it could be one of those other sensors as well. I may have to take it in to get a diag scan like CJM said, I was just seeing if I could save the money if I could find the problem on my own.

[chucked]

Sometimes a generic o2s will cause a light to throw but being a bosch you're probably ok. At this point in time you need to have it checked with a scanner like cjm said

[KKiowaTJ]

On upstream 02's IMO replace them both if one is bad the other isnt far behind. They are only good for 80k and should be replaced when you do a full tune up on newer obd II vehicles.

Id take it back for another, Bosch is a good brand, But can fail out of the box just the same as an AC one. When you took the old out, Was it running rich or lean?

Might be time for some new plugs and or tune up. But at 106k, Im pretty sure they are oem and if it were me id buy both up stream's. Clean the TB out and sensors etc. Thats the ****ty part of newer vehicles, Too many plastic parts and electronics.

[Pacheco_450r]

Thanks for the tips KKiowaTJ I've been told that even though the code read the front sensor that I should change the downstream as well. So if it is the actual sensors and not another problem I should probably just bite the bullet and replace the other 3 as well. I can take it back if you guys think it is a faulty sensor just to be safe. When I took out the old one it actually looked in great shape, no signs of being rich or lean. I replaced the spark plugs with factory AC delco iridium plugs at about 85k miles. I also cleaned out the throttle body and sensor. I completely agree with you about all the new technology and electronics, it's just that much more that can fail!

[CJM]

Honestly, Im not sure if its just toyota or what but I never had good luck with bosch parts. I replaced my O2's b/c they blew out (long story short they have the studs and can accept nuts but the exhaust shop welded the on).

I put bosch on first time around and my mpg dropped from 15 to 8, put denso on and back to 15.

Id replace them all anyways, usually whenone goes they all go.

[KKiowaTJ]

I could be wrong, But i have never had a problem with, But the down stream only relays the cat con heat, Nothing else. I cut my cat off one of my jeeps, Put a pipe with an 02 bung in and got 2mpg better and un-corked a bunch of power. But it might not be the same as mine was mopar and only have two total sensors.

But i would replace the up-streams only, bank 1 s1/bank 2 s1. I cant really remember the 'banks' on the newer 4.8, 5.3, 6.0 etc.

Has you mpg dropped at all? Thats usually the first sign of failing 02's. But if you have clean air flow, new plugs, No reason not to replace them to get it running top notch.

Wouldnt hurt to try and see if its a faulty sensor, Only out your labor to swap it. That way you dont spend what you dont need to. But then again IIRC you have to have your truck inspected and if there is a light they fail you?

If it were me id take back and swap in another new one, Clear the code with code reader and let it cycle again and see if it pops on. If it does, Go ahead with new 02's.

A good thing to buy if you have a smart phone is a OBD II blu tooth code reader. You can watch real time air flow, Fuel psi, 02's, MAP/MAF etc. They are only $20 bucks and you can read and clear codes as they come.

[Pacheco_450r]

My mileage did drop some but nothing dramatic it went from 19.5 hwy to 17 hwy.

Bank 1 Sensor 1 is the driver side upstream on these late model Chevrolets. From what I'm getting from everyone I'll return the one I bought with a new one just to be safe and replace the passenger side upstream sensor as well and see if it fixes the problem. If not I'll take it in to get a diagnostic scan to see if it's something electrical or another problem.


I appreciate all the input guys!

[CJM]

Curious, what kinda sliverado is this? Engine/cab size and 4wd/not? Im interested in a new truck as was thinking about chevys b/c I know they get pretty good mpg.

[Pacheco_450r]

It's a 2005 single cab, half-ton, 4wd with a 5.3L. It's a great truck, no complaints or problems til this engine light which I'm guessing is more of a time for extra maintenance thing. It's always had good mileage for a 4wd pickup.

[CJM]

Sounds pretty good Im in the market for an 05-8 silverado or comparable F150. I find if you get the towing package tho mpg kinda drops (and I need that sorta thing lol).

let us know how this sensor fiasco goes, Im willing to bet you just need to replace them all (or at least the fronts) and it should be ok.

[Pacheco_450r]

After replacing the same o2 sensor again as well as the passenger side front, I still got an engine light. I took it in for a diagnostic scan and while the scan would say the o2 sensor was failing, they tested the sensor and it was working just fine. They recommended that I re-flashed the PCM to reset it ($50). After having it re-flashed the engine light shut off, and I can't get it to turn on again even when trying to. I'm glad it wasn't an expensive fix! This is a good example of how technology isn't always so reliable, although I still love this truck!