Check Engine light for rear O2s won't go away

[mystic96]

For the better part of a year I've had this check engine light on for the rear O2 sensors being bad. I've never really cared to mess with it because I guess after having off road H pipes on my Mustangs for so long it's never really bothered me. And I could always hook up some MIL eliminators and be done with it.

Well now time's come around to get my inspection done and obviously it won't pass with the check engine light on and the O2 sensors testing bad.

According to the codes stored in the computer, both the bank 1 and bank 2 after cat o2 sensors are showing low voltage (I think one was code p0 137).

I replaced both sensors, reset the computer, drove around for a while and the check engine light came back on pretty quickly. I rechecked the codes and again it was the same 2 codes as before, both the left and right rear o2s weren't working right.

So before I go and replace the sensors again, what could be making the sensors read bad? I don't think both the sensors would go bad and then my luck would be to buy 2 new ones that are also bad. Just doesn't really add up.

[whitetrash]

Does this car have cats? If not it's gonna throw a code quickly

[mystic96]

Yes, it's on my '00 Silverado 5.3L

it's all stock and yes it still has it's factory cats.

I guess if I could just get some O2 sims or MIL eliminators or whatever they're called now days, I'd just do that and not worry about it but it seems they've been outlawed for some time now.

Can I just have them tuned out with a tuner and have it still pass the OBD-II scan to get it inspected?

[Scott Mc]

You need O2 eliminators edit, too late

[fastwhite99gt]

You can turn them off in the tune and pass, you're allowed one emissions system status not ready.

[034V]

yup.. tune 'em off..

or try the old Ford way..

[Probie]

You can turn them off in the tune and pass, you're allowed one emissions system status not ready.

What about other things ie: camshaft sensor timing.

[fastwhite99gt]

Mine are not even put in the exhaust at all, we just deleted the codes in the tune. The light never turns on and on the readiness monitor, the O2 sensors always show not ready. The evap, catalyst, misfire, and the other monitors work fine. We did have to turn the threshold for the misfire code sky high because of the cam in the truck, but it works fine. If there is something wrong that turns the light on, they won't pass it. There can be codes, just none that are supposed to turn the check engine light on.

[JC316]

You can turn them off in the tune and pass, you're allowed one emissions system status not ready.

Two incomplete on one that old.

[fastwhite99gt]

Two incomplete on one that old.

Ah, didn't know that. Mines an 06 and the guy here in El Paso told me just one. I did have to put cats back on it, but it toned the exhaust noise down so I didn't mind too bad. Just a PITB to put them right off the header collectors before the bend in the Y-pipe on the driver's side and then right off the header before the merge on the passenger side.

[mystic96]

So basically no reason to try and correct the problem? Just eliminate the code from the computer?

How much does it cost to tune that out?

[S_K]

This code usually means clogged Cats. Maybe I have been lucky, but a bottle or two of Lucas Total Fuel System cleaner has solved it for me.