turabo87

Happy Fathers Day guys!!

Im kinda bummed out that I have 4 new O2 related codes that came right after having my exhaust fixed. Not a coincidence if you ask me. Let me be more specific. A portion of 3” exhaust had to be cut (in between the X of the X pipe and after the collectors and primary O2s, because the exhaust had direct contact with the tunnel of the under body. Long story short, job was done yesterday morning by the exhaust shop and the new piping looked great. I drove the car all day, I did multiple trips and had no issues. Then at night I was going to take the car out, I started and left it idling for a couple of minutes and when I come back the check engine light is ON.

Codes are the following:
P0134 - Circuit Insufficient Activity Bank 1 Sensor 1
P0154 - Circuit Insufficient Activity Bank 2 Sensor 1
P1133 - Insufficient Switching Bank 1 Sensor 1
P1153 - Insufficient Switching Bank 2 Sensor 1

I have a catless setup so the primary 02s are the only ones to worry about. Are these codes typically signs of damaged 02 sensors or disconnected/damaged wiring of the 02s, or could it be something else?

Please help before I go confront the shop or I get new 02s. Thanks.

Fastbird

Have you gotten under the car to see if they're plugged in or damaged at all?

Looking at your exhaust I'd guess you have headers. Did you use extensions for the fronts that converted the connection to a square pin (thus making it possible the shop plugged back into the wrong set of connectors......)

STRMLNE

My guess is that exhaust dude in the pic made a mistake.

turabo87

My guess is you’re right. I’m gonna buy two new O2s and keep the receipt and go with them back to the shop. If it comes to that they damaged the old O2s, I’ll have them there for them to change and let’s see how they make up for it. Hopefully it’s just disconnected O2s. Pisses me off, but oh well, things happen.

STRMLNE

It’s pretty hard to damage them. I would have them look over their work before you start buying parts.

turabo87

Update: Went this morning back to the exhaust shop and we carefully looked over everything. We found nothing wrong with the O2's and nothing wrong with their work. They never disconnected the 02's to start with (they cut part of the x downstream of the 02's and replaced with a new piece). Everything looked perfect, wiring looks fine too. Nothing looks damaged or different. Also, there are no signs of leaks anywhere by the clamps of the Xpipe; everything is perfect. As a precaution, I disconnected the plugs and dabbed the pins with di-electric grease and plugged them back in, but it's making no difference. Looks like it has nothing to do with a mistake they made at all.

So far I can only boil it down to two theories:
1. The most unlikely one I see is that both 02 sensors took a crap maybe with the vibration of the saw when they cut the exhaust or maybe some impact when they were fitting the X pipe back in. I say highly unlikely because BOTH 02's went out then at same time (unlikely if you ask me).
2. Maybe the exhaust flow characteristics changed with the exhaust bypass mod that was done that same day in the muffler shop. I didn't specify earlier that that day 2 things were done to the exhaust: They refabbed a section of the X pipe that had interference with the tunnel and I had them do the "exhaust bypass mod" on my mufflers. So my theory is that maybe this muffler bypass changed the flow characteristic and exhaust temp at the 02 locations enough that the 02's are reading out of range. As far as I understand, these 02 sensors are narrow band and just read RICH or LEAN conditions as a binary reading, so I'm understanding by the codes that they're not switching enough between reading RICH and LEAN.


Really weird either way. On the plus side, I talked to my tuner and worst case he can turn the codes off but I'd like to get to the root of the issue and not just mask the codes. I need some help on what should I do next, I'd like to try not to change O2 sensors without being certain they're bad.


Muffler bypass mod done simultaneously that day too.

turabo87

Yes I have headers: Texas Speed 1-3/4 Long tubes. I have extensions for the fronts 02's but they're the flat inline 4 style plug. You can disregard this completely since they never disconnected anything and I visually confirmed today that everything looked perfect and unmolested.

PS: I did some research on other threads here related to these codes and looks like it's not uncommon for these codes to pop with long tube headers. It's just curious that the muffler bypasss mod provoked this. I've had the long tubes and this tune for about 5k miles and never saw this code before until now with the bypass mod. The more I think of it, the more I believe that the exhaust flow and temp characteristic changed and maybe my primary 02's are just not in an optimal heat range of operation anymore.

Bill Curlee

There is a FUSE for the O2 sensor heaters OXYSEN Fuse # 15 in the under hood fuse block. The heaters MUST work for the sensors to survive and function properly. Measure the voltage on top of the fuse test points to ground (KEY IN ON) and insure you have full battery voltage.

You should also monitor O2 sensor function with a scan tool.





Bill

turabo87

Hi Bill, should I measure the voltage drop from 'Hot In ON' to "G105"?

Robrote

I'm thinking out loud, but haven't I heard that grounding the mig welder on the exhaust has a potential to mess with whatever electric devices are also grounded on them?

Bill, tell me I dreamt that.

turabo87

FYI, they welded the new section of pipe with the midpipe removed and out of the vehicle in a separate area. The only portion that I saw that they did weld on the vehicle was part of the welds of the muffler bypass, far away from the O2's. I haven't done the diagnostic check that Bill recommended yet. I plan to do that voltage check today after work.

turabo87

Bill, I checked voltage from top of fuse 15 (OXY SEN) to ground and I have full battery voltage. I’m at 12.4V key on, 13.8-14V running at idle. Fuse 15 has continuity too.

I plan to check O2 activity with my tuner same day he masks my codes for the check engine light.

tblu92

Lt headrs create numerous running issues That is why they are illegal in most states With LT's the front 02 bungs are moved about 3 ft further aft than the stock locations The front 02's are NOT designed to read accurately this far back They will read rich as they do not heat up properly
There is no 100% fix However ther are a few things that can help the readings
1 Lower the front 02 swithching points like 100 points on each side Ideally you want your front 02;s to have an average at P/T from .400 to .500 millivolts --- LT's RAISE this average- higher means richer
2 Many people have had success by installing the REAR 02's onto the front locations as the rears are far more sensitive
Finally It is always recomended to dis connect the battery while doing welding on your exhaust---as the electronics can take a voltage spike and ruin the sensors This rarely happens but i have seen it happen a few times--Most all muffler shops never dis connect the battery Not saying this is what happened but it has happend before !
PS front 02 voltages normally change from a low of .100 to a high of .950 millivolts with an average from .400 to .500
IF your fronts 02's aren't changing and are stuck on .450 that means they are JUNK !!

Bill Curlee

Excellent info!! Thanks for sharing.

turabo87

This is really good info. With my tuner this weekend, first thing we'll do is check front O2 activity. If they work, then I'm gonna ask my tuner to lower the switching points as he sees fit, and mask the codes too for future just in case.

Bill Curlee

Let us know what the tuner finds wrong and how the new tune turns out.

BC

turabo87

I want to provide closure to this issue. Trublu92 was correct. After having now an HPTuners MPVI, I checked O2 activity and they're fine. It was just what you said about them reading richer. Now I should adjust the switching point like you said, but I don't have a widebandO2 gauge to confirm that my adjustment is accurate. I guess I could just start with 100 points like you said and monitor my fuel trims and use that for feed back.