Service Engine Soon Light on....Please help

[divo]

2000 Chevy Silverado 2500 6.0 Codereader reads 4 codes. They are as follows...
P0140 Bank 1 Sensor 2 Sensor CKT no activity

P0 160 Bank 2 Sensor 2 Sensor CKT no activity

P0140 Bank 1 Sensor 2 Sensor CKT no activity

P0160 Bank 2 Sensor 2 Sensor CKT no activity

This truck has 4 oxygen sensors. 2 in front of the cats, 2 after the cats. I just replaced the two after the cats( $75 each) with Bosch #15733 universal sensors. wired per instructions. purple to black, tan to grey, 2 whites to 2 dark brown. Erased the codes and all was good till I drove about 10 miles. The S.E.S. light came back on with the same codes. last year I replaced all 4 of them beacuse it had those codes plus the codes for the front ones. I believe they were smoked by a bad fuel pressure regulator which I had to replace at the same time. After replacing all four....the codes for the fronts went away but the existing codes never went away. I rarely drive it, but figured it was time to finally fix it. Fuses are good. What else could it be? Why am I getting 2 of each code? Thanks

 

[Reel Poor]

Re: Service Engine Soon Light on....Please help

O2 sensor diagnostics can get indepth pretty quick. You going to need some diagnostic charts. And whatever you do don't use a test light to aid in your diagnostics.

You may be getting those duplicate codes because one set is active and the other set is in the history.

I can tell you those universal sensors are a real P.O.S.
I would advise if your going to replace them buy what fits (OEM) and not what you have to make fit.

 

[Autotech1]

Re: Service Engine Soon Light on....Please help

sensor one is in font of the cat.

sensor two is behind the cat

bank one should be the odd side 1 3 5 7

bank two should be evens 2 4 6 8

its odd that they both went out, its possible they share a refrence voltage. actually i believ they generate theyre own votage. dissimellar metals, heat, and some black magic i believe

use a digital volt meter. they should generate 0-5V dc.

If they are hearted sensors they may not be getting the heating voltage, that could be shared check for voltage on the heating circuit.

if the sensors are bad expect to pay out the taterhole on this one.

 

[dolluper]

Re: Service Engine Soon Light on....Please help

Beware don't poke those wires as one is not a wire,having no activity generally means the harness is screwy,harness kits are availlible from most dealers and aftermarket for the HEATED O2 sensors,other poss is you have installed the wrong sensors

 

[divo]

Re: Service Engine Soon Light on....Please help

Thanks for the replies. Tonight when I get hame I will trace the harness back as far as I can. There is a fuse for the 2 fronts and another fuse for the 2 backs in the fusebox under the hood. I visually checked those last night and they looked good. Will check with Fluke later to verify. I have had, and still have some grounding issues with this truck. One of the leads on the oxygen sensor is a ground....can I just run my own to the engine block temporarily to see if it clears? Thanks

 

[dolluper]

Re: Service Engine Soon Light on....Please help

Me thinks you just fixed it,well sort of you now know the cause of your codes THE GROUNDING ISSUE.Check and clean all your grounds!!!!!Drill a small hole in your exhaust pipe install a sheet metal screw with a wire to a frame ground wherever it's handy

 

[divo]

Re: Service Engine Soon Light on....Please help

OK...just checked it out. I have 12 volts at the sensor on the 2 heater wires (dark brown) while the truck is running. I get no continuity(sp) between the ground(tan) wire and anywhere within reach of the meter lead including the sensor. That means the ground wire is not grounded (the truck was off when I tested the ground). It got dark so I gave up for the night. I will try to trace the harness tomorrow...That wont be an easy task. I am searching for a wiring diagram. I am wondering if I can just run my own ground to the engine block or is the factory one filtered or protected in any way. Thanks

 

[divo]

Re: Service Engine Soon Light on....Please help

Tonight I tried to trace the wire harness. I followed it past the tranny but I lose it when it crosses over the bell housing. Then I cant find it under the hood....Does it go to the ECM which I believe is near the glovebox? If so, tomorrow I will See what its going to take to get to the connections there. The harness crosses over the bellhousing right at the joint where it bolts to the motor...the tranny has been out of the truck 3 times(2 times at dealer under warrenty, 1 time by me because mechanic at dealer is a hack). I am starting to wonder if the harness is crushed in that joint. I would like to be able to ohm that harness out. So my question is....does the harness from the o2 sensors go the ECM? Thanks

 

[Plainsman]

Re: Service Engine Soon Light on....Please help

Can of Seafoam fixed mine back in April, hasn't been on since.

 

[Skinnywater]

Re: Service Engine Soon Light on....Please help

Me thinks you just fixed it,well sort of you now know the cause of your codes THE GROUNDING ISSUE.Check and clean all your grounds!!!!!Drill a small hole in your exhaust pipe install a sheet metal screw with a wire to a frame ground wherever it's handy

divo.....I've got a lot of credentials in the auto business. I didn't post because dolluper I believe, has you covered.
Have you performed his suggestion?

 

[divo]

Re: Service Engine Soon Light on....Please help

Me thinks you just fixed it,well sort of you now know the cause of your codes THE GROUNDING ISSUE.Check and clean all your grounds!!!!!Drill a small hole in your exhaust pipe install a sheet metal screw with a wire to a frame ground wherever it's handy

divo.....I've got a lot of credentials in the auto business. I didn't post because dolluper I believe, has you covered.
Have you performed his suggestion?

The ground wire on the sensor is isolated from the body of the sensor....if I ground the exhaust...the sensor still wont be grounded, just the body of the sensor. I would like to find the actual problem before adding a wire( hopefully). Thanks

 

[dolluper]

Re: Service Engine Soon Light on....Please help

Well yes it goes to the computer,check on the top of the bell housing where the harness crosses there should be a ground on the upper trannie bolt,now the plot has thicken ,trannie out three times,would have been useful info the first post.I think you will find the ground is not connected or ripped apart
Can you tell us what engine your running????

 

[divo]

Re: Service Engine Soon Light on....Please help

Thanks for the reply....I will check that ground connection when I get home. The engine is a 6.0. Thanks.

 

[Reel Poor]

Re: Service Engine Soon Light on....Please help

There should be some brackets mounted to the bellhousing bolts. These brackets hold connectors for the O2 sensor harness. From there there should be pigtails from the main engine harness with connectors that mate with the individual O2 harnesses. I'll bet Buba either didn't connect them, pinched them in the bellhousing, or pulled/tore the wire(s) out of the harness connectors. Look close in the connectors, just because the wire has not been pulled completely out of the connector does not mean the terminal pin is in it's proper location either, look close.