Diagnostic Help Needed

[VetPet]

My check engine light came on while I was logging some data and when I checked them with my scan tool here's what I found.



Could anyone help me with diagnostic help for these codes? I'm finding it hard to believe that all four sensors could be acting up at the same time. I've recently done some exhaust work (new cats & X pipe) and that's when I started getting the codes. I did clear them twice and they came back. If anyone can help me with this it would be appreciated.

Thanks,

[Black02SS]

Looks like the O2's are bad now. You can eliminate any of them that are for the rear as those don't really mean much. For the fronts if you are showing these codes, then the car is in Open loop and not relying on them for any compensation. You have a few options. Replace the sensors and get a decent tune in the car, run in constant open loop all the time, or fiddle with the settings to try and help the switching problem. I have seen this countless times.

[joecar]

All 4 sensors at the same time...!

Inspect their connectors, make sure they are plugged in all the way and that they are not damaged.

[eboggs_jkvl]

Did you just put LTs on? All 4 at once is very unusual. New LTs sometimes equate to melted wiring down below.

I need to read better. Look for bad connections, no connections or melted wiring.

E

[Ira]

Or a bad fuse, that might take out a bunch at once.

Ira

[VetPet]

Thanks guys. Appreciate all of your feedback. I'm going to look at the fuse box first as this would be the easiest and simplest thing to check. Then I'll move down the list from there. I'll let you guys know if I find out anything.

By the way. if a fuse blows and there's no power to the sensors, does the PCM go into open loop automatically and use the VE table for fueling? I was running with the MAF enabled when I was logging my data in order to get the MAF dialed in.

Regards

[VetPet]

Well, checked the fuse and found that it was blown. Don't have any mini fuses so tomorrow I'll buy some and put one back in. I'll clear the codes before I start the car again and then drive the car to see if the codes come back. Hopefully it was just a one time occurrence and the fuse doesn't blow again. If it does, I guess that means there's some kind of short occurring in one of the sensors. Since the issue didn't start until after I installed my hi-flo cats and X pipe I'm going to assume that the problem has to be with one of the rear O2 sensors. I'm guessing that I could have damaged one or both of them during removal or installation when you're turning them. Why couldn't they put a connector at the top of the sensor so you could disconnect them before removal. I guess that would be too logical. I'll keep you guys posted.

[joecar]

Mental note (to myself): good point, check fuse first.

[Ira]

Mental note (to myself): good point, check fuse first.

I've always been a fan of starting with the easy stuff! Not to say that the fuse isn't just hiding another problem, but it seemed like the right place to start.

Ira

[VetPet]

Replaced the fuse, cleared the codes and went for a drive. No more check engine light! I'm guessing that when I removed and reinstalled the rear O2 sensors that the twisting around of the sensor did something to the wires in the harness to cause a short. The harness might have relaxed enough now to eliminate any pinching that might have taken place. I guess I should have disconnected the harness first before taking the sensors out but it's such a pain. Anyway, all is good now. Thanks everyone.