[Icysheet]

Hello!

My check engine light went came on and after checking with MHD, it seems my O2 sensor post cat is dead. After popping the hood and taking a look at it, I noticed that the wire for the post cat O2 sensor was fully taught with no play at all. This resulted in the wire coming out of the O2 sensor and bending 90 degrees immediately to go up to the connection on top of the engine. I can't remember if it was like that when I installed the Wagner catted downpipe last year, but that's how it is now.

Has this happened to anyone else? I'm assuming if I just replace the sensor, the same problem will happen again in the future.

I see two possible solutions:
1. Use a combination of the old sensor's wiring and a new sensor to make a slightly longer overall O2 sensor and wire. Possible change in resistance causing an issue?
2. Somehow loosen the downpipe and rotate it to provide some slack on the O2 sensor and then replace the old sensor with a new one.

Thoughts?

[thejeremyman9]

I believe there was a batch (if not all) wagner DPs reported to have this issue, so it might be unavoidable, but you can try rotating incase it is due to install orientation and not O2 bung placement.

This video talks about buying sensors and splicing them. Assuming you do the connections well, the slight change in wire length shouldnt have any impact on the resistance/readings.

Some people also run without using some of the wire clips, but be careful it doesnt get too close to anything that can melt it.

[Icysheet]

You're the best! Thanks so much, this is really helpful.

[pw0n]

Appreciate the video, thejeremyman9

I have the same issue with my Wagner catted downpipe. Others have reported this issue - I recall seeing a few threads but this one comes to mind, https://f30.bimmerpost.com/forums/sh....php?t=1699972

Anyways, I'm getting a CEL for 12B304. Wouldn't be surprised if I broke the O2 sensor as I had to tug and pull on it pretty hard to get it to connect. Would like to resolve this issue ASAP, but not sure if replacing it with a new one of the same exact length will resolve it.

That said, I haven't tried myself so wondering - anyone in our shoes w/ the Wagner fitment issue who was able to successfully resolve their CEL using an OEM O2 sensor replacement? And if so, how long have you been running the replacement sensor?


On another note, been considering going down the route in the video shared above mainly because it allows the O2 sensor to be extended a bit.
Based on my quick research, it looks like Bosch offers two types of universal O2 sensors, Bosch 15732 for downstream and Bosch 15733 for upstream. That said, I'm looking at Bosch's website for our O2 sensor (see Bosch 16046), and in their description, there's a column for "Specific Or Universal Fit", and our part is marked as "Specific". Not sure if this holds any bearing, but I'm wondering if we're able to use the Bosch 15732 - I'd imagine the term "universal" means exactly that, but I don't want to rely on my assumptions this time

Anyone know if the universal "extension" will work for our cars? If not, are there any other options to extend the downstream O2 sensor?

[thejeremyman9]

Originally Posted by pw0n

Appreciate the video, thejeremyman9

I have the same issue with my Wagner catted downpipe. Others have reported this issue - I recall seeing a few threads but this one comes to mind, https://f30.bimmerpost.com/forums/sh....php?t=1699972

Anyways, I'm getting a CEL for 12B304. Wouldn't be surprised if I broke the O2 sensor as I had to tug and pull on it pretty hard to get it to connect. Would like to resolve this issue ASAP, but not sure if replacing it with a new one of the same exact length will resolve it.

That said, I haven't tried myself so wondering - anyone in our shoes w/ the Wagner fitment issue who was able to successfully resolve their CEL using an OEM O2 sensor replacement? And if so, how long have you been running the replacement sensor?


On another note, been considering going down the route in the video shared above mainly because it allows the O2 sensor to be extended a bit.
Based on my quick research, it looks like Bosch offers two types of universal O2 sensors, Bosch 15732 for downstream and Bosch 15733 for upstream. That said, I'm looking at Bosch's website for our O2 sensor (see Bosch 16046), and in their description, there's a column for "Specific Or Universal Fit", and our part is marked as "Specific". Not sure if this holds any bearing, but I'm wondering if we're able to use the Bosch 15732 - I'd imagine the term "universal" means exactly that, but I don't want to rely on my assumptions this time

Anyone know if the universal "extension" will work for our cars? If not, are there any other options to extend the downstream O2 sensor?

Does the O2 bung placement also cause your O2 sensor to hit against the firewall or any other part? That's what another persons problem was in the MHD thread recently.

As far as extending the wires goes, you can just extend them yourself if you want... just buy some wire, ideally the same gauge, and splice in some new wire to extend the length. This is how any wiring harness is "manually" extended, whether you need it for a wire tuck, engine swap, or something simple like different sensor placement. Buying a sensor that has a longer harness but still requires splicing just means you only have to solder once and not twice.

[Orion4]

If OP decides to splice in some small amount of additional wire to reduce the stress, definitely use the same gauge and type of wire. Otherwise you may change the impedance. O2 sensor accuracy is impedance sensitive.

Originally Posted by thejeremyman9

Does the O2 bung placement also cause your O2 sensor to hit against the firewall or any other part? That's what another persons problem was in the MHD thread recently.

As far as extending the wires goes, you can just extend them yourself if you want... just buy some wire, ideally the same gauge, and splice in some new wire to extend the length. This is how any wiring harness is "manually" extended, whether you need it for a wire tuck, engine swap, or something simple like different sensor placement. Buying a sensor that has a longer harness but still requires splicing just means you only have to solder once and not twice.

[pw0n]

Originally Posted by thejeremyman9

Does the O2 bung placement also cause your O2 sensor to hit against the firewall or any other part? That's what another persons problem was in the MHD thread recently.

As far as extending the wires goes, you can just extend them yourself if you want... just buy some wire, ideally the same gauge, and splice in some new wire to extend the length. This is how any wiring harness is "manually" extended, whether you need it for a wire tuck, engine swap, or something simple like different sensor placement. Buying a sensor that has a longer harness but still requires splicing just means you only have to solder once and not twice.

Thankfully not the case - but not sure if that's due to Wagner having inconsistent designs or if it's due to a difference in chassis (I own an F32 RWD).
See below for an image - doesn't touch the firewall but it looks very uncomfortable being bent at a sharp 90° angle


I did a bit more digging, and it looks like the PWG F30's (same N55B30M0 engine, I think) use part 11787645875 (Bosch 16417) for the downstream sensor. It's apparently 690mm vs 550m on the 16046.
I know the PWG and EWG F30s have different downpipes, but I'm curious to know if the downstream sensor can be used for the EWG models.


In either case, I believe I heard in the video that you can't solder O2 sensors, which probably explains why Bosch's universal fit sensor includes a "fancy" splice connector. I'm sure there are cheaper alternatives, but at $40, I'd go for it if I can guarantee a fix. Worst case, assuming my sensor is shot, I suppose I can extend the O2 sensor by frankensteining together a new O2 sensor and the universal kit.

[thejeremyman9]

Originally Posted by pw0n

Thankfully not the case - but not sure if that's due to Wagner having inconsistent designs or if it's due to a difference in chassis (I own an F32 RWD).
See below for an image - doesn't touch the firewall but it looks very uncomfortable being bent at a sharp 90° angle


I did a bit more digging, and it looks like the PWG F30's (same N55B30M0 engine, I think) use part 11787645875 (Bosch 16417) for the downstream sensor. It's apparently 690mm vs 550m on the 16046.
I know the PWG and EWG F30s have different downpipes, but I'm curious to know if the downstream sensor can be used for the EWG models.


In either case, I believe I heard in the video that you can't solder O2 sensors, which probably explains why Bosch's universal fit sensor includes a "fancy" splice connector. I'm sure there are cheaper alternatives, but at $40, I'd go for it if I can guarantee a fix. Worst case, assuming my sensor is shot, I suppose I can extend the O2 sensor by frankensteining together a new O2 sensor and the universal kit.

You might be right about the soldering. Im not 100% sure for the O2 sensors. I have extended/repaired harnesses before on my 3000gt by soldering in new wire without any negative consequences, but it wasn't an O2 sensor, and its a 30 year old car lol.

That angle is definitely not good, but at least a longer wire should solve the problem since its not hitting anything.

I am not sure about the interchangeability of the sensors between PWG and EWG. I would be a little concerned, without conformation, that it would "work" but may not send exactly the same signal the DME is expecting, so the data the DME gets and thinks is accurate is not infact.

[Possessed]

I have the same issue with my M235i EWG. Got the catted Wagner DP installed last month and the shop told me that the O2 monitor cable was too short (it's 550 mm) and dangerously close to the manifold.

Took some photos and asked the dealer I purchased it from to check with Wagner, and the reply was "unattach it from the clips and you'll be fine". Not particulary happy with Wagner's response.

Seems that all the EWG N55's use the 550 mm sensor, so I'm also interested if a PWG sensor would work, or if splicing is the only option.

[thejeremyman9]

Originally Posted by Possessed

I have the same issue with my M235i EWG. Got the catted Wagner DP installed last month and the shop told me that the O2 monitor cable was too short (it's 550 mm) and dangerously close to the manifold.

Took some photos and asked the dealer I purchased it from to check with Wagner, and the reply was "unattach it from the clips and you'll be fine". Not particulary happy with Wagner's response.

Seems that all the EWG N55's use the 550 mm sensor, so I'm also interested if a PWG sensor would work, or if splicing is the only option.

So much for Wagner claiming its 1/500 that have the issue. This is the most common issue across all DPs, so it's really surprising its still happening. Either a poorly designed jig or just inconsistent production... Their response to other people said to "stretch the wire" lol

[Korvo]

Originally Posted by thejeremyman9

So much for Wagner claiming its 1/500 that have the issue. This is the most common issue across all DPs, so it's really surprising its still happening. Either a poorly designed jig or just inconsistent production... Their response to other people said to "stretch the wire" lol

This is so crazy. I can't believe that's an actually response they sent to a customer.

Guess I'll add Wagner products to my "do not buy" list.

[glitch_modulator]

I'm having the same issue with the wagner catless downpipe on my f30 n55. The secondary o2 sensor wire is too short. I even pulled out all the clips and its still short to connect. Were you able to address this issue?

[thejeremyman9]

Originally Posted by glitch_modulator

I'm having the same issue with the wagner catless downpipe on my f30 n55. The secondary o2 sensor wire is too short. I even pulled out all the clips and its still short to connect. Were you able to address this issue?

It's a manufacturing issue with the DP. Suggest contacting wagner and be prepared to send it back.

[wwmiller3]

I don't have a Wagner--I have a high-flow catted SuperSprint--that creates the same situation of the downstream o2 sensor cable length being too short. When I did the initial install, I spliced in extra wire length to make up for the difference. This worked for a number of years, but when I went back in to install an upgraded turbo, the o2 sensor failed with 12b304.

Now, it is possible I did some damage on removing the downpipe for the turbo install, but I doubt it as I was extra careful. I suspect the wire joints eventually failed (higher resistance). I ended up replacing the downstream sensor with a new OEM one (too short again), but I rerouted the o2 connector that normally is clipped on the valve cover to behind the engine at the firewall. This gave me the extra length I needed and also kept the wires away from the hot turbofold. That's one option if you want to keep the stock sensor and do a little rerouting of wiring.

[123Britt]

I don't think it is a manufacturing flaw but due to the design - the aft 02 sensor must be located a little further out.

In my 15" 235i fitment was great and the unit has worked great! For the 02 wire routing all I did was unclip the (2) locations and routed to (1) only. Still keeping the top hold down clip bracket and with a straight wire run to the sensor itself. Not super tight but about 1" deflection and the bend radius is acceptable.
.
.
Yes - I think Wagner should be more straight forward about the location of the sensor --- but it does work and I could not be happier with the DP function , sound and performance.

[n55david]

Originally Posted by 123Britt

I don't think it is a manufacturing flaw but due to the design - the aft 02 sensor must be located a little further out.

In my 15" 235i fitment was great and the unit has worked great! For the 02 wire routing all I did was unclip the (2) locations and routed to (1) only. Still keeping the top hold down clip bracket and with a straight wire run to the sensor itself. Not super tight but about 1" deflection and the bend radius is acceptable.
.
.
Yes - I think Wagner should be more straight forward about the location of the sensor --- but it does work and I could not be happier with the DP function , sound and performance.

yes. its a flaw.

[thejeremyman9]

Originally Posted by 123Britt

I don't think it is a manufacturing flaw but due to the design - the aft 02 sensor must be located a little further out.

In my 15" 235i fitment was great and the unit has worked great! For the 02 wire routing all I did was unclip the (2) locations and routed to (1) only. Still keeping the top hold down clip bracket and with a straight wire run to the sensor itself. Not super tight but about 1" deflection and the bend radius is acceptable.
.
.
Yes - I think Wagner should be more straight forward about the location of the sensor --- but it does work and I could not be happier with the DP function , sound and performance.

It's one or both. The secondary O2 placement was either incorrect (in terms of vertical position and/or orientation as compared to stock) by design, or it was correctly designed but manufacturer out of spec, or both. But the placement is incorrect (on at least some units) and theres tons of examples on the forums of people encountering this issue. You just happened to get one where it does work.

[paimon.soror]

FWIW i had to run mine without using most of the clips (i have a catless version) and it fit fine. I dont have a harsh angle like that.

[pw0n]

Originally Posted by wwmiller3

I don't have a Wagner--I have a high-flow catted SuperSprint--that creates the same situation of the downstream o2 sensor cable length being too short. When I did the initial install, I spliced in extra wire length to make up for the difference. This worked for a number of years, but when I went back in to install an upgraded turbo, the o2 sensor failed with 12b304.

Now, it is possible I did some damage on removing the downpipe for the turbo install, but I doubt it as I was extra careful. I suspect the wire joints eventually failed (higher resistance). I ended up replacing the downstream sensor with a new OEM one (too short again), but I rerouted the o2 connector that normally is clipped on the valve cover to behind the engine at the firewall. This gave me the extra length I needed and also kept the wires away from the hot turbofold. That's one option if you want to keep the stock sensor and do a little rerouting of wiring.

Apologies for bumping an old thread - but wwmiller3 , how did you manage this? I tried this myself, and was unable to reroute the O2 connector behind the engine. Any tricks I should be aware of? For reference, I have an F32 435i.

[thejeremyman9]

Originally Posted by pw0n

Apologies for bumping an old thread - but wwmiller3 , how did you manage this? I tried this myself, and was unable to reroute the O2 connector behind the engine. Any tricks I should be aware of? For reference, I have an F32 435i.

You basically just dont use the OEM clips and route the wire with the straightest path possible from CP to harness. I assume you got a DP that doesn't fit properly due to incorrect O2 bung placement, so the other option is to contact that manufacturer/vendor for the DP.

[pw0n]

Originally Posted by thejeremyman9

You basically just dont use the OEM clips and route the wire with the straightest path possible from CP to harness. I assume you got a DP that doesn't fit properly due to incorrect O2 bung placement, so the other option is to contact that manufacturer/vendor for the DP.

That hasn't worked for me, unfortunately. Curious to know miller's method of routing it "behind the engine at the firewall".
Unless you two are referring to the same methodology - in which case, it'd be on the side of the engine for me (and as simple as unclipping it, no "routing" necessary).

[thejeremyman9]

Originally Posted by pw0n

That hasn't worked for me, unfortunately. Curious to know miller's method of routing it "behind the engine at the firewall".
Unless you two are referring to the same methodology - in which case, it'd be on the side of the engine for me (and as simple as unclipping it, no "routing" necessary).

Going behind the engine would only be a shorter path if your O2 bung on the DP was placed further in that direction (i.e., more on the "top" or side of the DP toward the center of the car). If your O2 bung is placed incorrectly the other direction, the side of the engine would be shorter. So basically, you just run it the shortest/straightest path possible, and if that doesn't work, your O2 bung is too far off.