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98 328i P0155 Engine Code

7K views 15 replies 6 participants last post by  MINIz guy 
#1 ·
Bank 2 Sensor 1... where is this located? I know Bank 2 means after the Catalytic converter. But this just came up yesterday when the temperature was at 5 degrees. I figure I let the car warm up, drive it around, then reset the code and see if it goes away. I got the engine warmed up, drove for quite a bit, then pulled over to a parking lot and reset the code. Turned the car back on, CEL goes away. Then maybe 5 seconds later comes back. Another scan, same thing: P0155 Bank 2 Sensor 1 heater circuit O2 sensor failure.

I had just replaced both of the Bank 1 sensors (on the headers) last year and I know one of the causes for the P0155 is usually faulty Bank 1 sensors... but I dunno. Not happy since OBD2 sensors are not cheap. The Dealer wants $200 a pop (my price). Nappa has the NGK O2 sensors for $109 a pop, Denso for $112 a pop, and Bosch for $124 a pop. Now since my Bank 1 sensors are Bosch, would it be OK if I go with the OEM NGK O2 sensors for Bank 2 or shall I shell out the $124 and get Bosch ones for the rear as well?

Not happy about this. I hate the cold, hate the snow, hate the ice, love the car. :cry:
 
#3 ·
***8226;O2 Heater element resistance is high
***8226;Internal short or open in the heater element

***8226;O2 heater circuit wiring high resistance
***8226;open or short to ground in the wiring harness


It does suck working on a car in the winter...

Honestly... Sometime when and if i have to work on a car in the cold.. Ill just use the other car until i can find the wilpower to want to do it..

:(

With the weather being the way it is.. Id look at the wiring maybe you ate a ice ball of something... pinched a wire..
 
#4 ·
•O2 Heater element resistance is high
•Internal short or open in the heater element

•O2 heater circuit wiring high resistance
•open or short to ground in the wiring harness

It does suck working on a car in the winter...

Honestly... Sometime when and if i have to work on a car in the cold.. Ill just use the other car until i can find the wilpower to want to do it..

:(

With the weather being the way it is.. Id look at the wiring maybe you ate a ice ball of something... pinched a wire..
Ahh good point. I didn't consider that. I know my car underneath is an ice box, but I could have hit something and jacked something up.

And yeah, tell me about it. I am working on restoring the M-Tech ground up with new seals, trim, basically cosmetics. I went through two propane tanks from trying to heat the garage up. At least my headliner is back in the car. Good lord... so much easier when the weather is warmer.

Thanks for the heads up, chief. And thank you as well Jakobie.
 
#5 ·
So I checked underneath... sure enough, whatever I hit and bounced up hit the wire. So the O2 sensor needs to be replaced. Might as well replace the other side as well, while I'm at it. Oye...
 
#6 ·
Alright, replaced the O2 sensor... P0155 has come back. Now I am lost and unnerved. Anyone that can give any pointers? Burning2nd? I'm trying to avoid going to the dealership to get it looked at since I don't know if my guy will be in.

Any help would be greatly appreciated. I am hoping it is not a short.

I should note that it took a good while for the P0155 to come back again. I drove half the day with the light off only for it to come back as I was heading home after a good drive. I am thinking the cold has something to do with it? I can't explain why it would go away and then just come right back after half a day.
 
#9 ·
By the way, after some thought... bank 2 sensor 1... is that on the header? Bank 2 sensor 3 would be post cat, correct? Same with Bank 1 sensor 4? I wonder if I just wasted money on the wrong set of relays...
 
#10 · (Edited)
yes, bank 2 sensor 1 is on the header, pre cat.

they are designated bank 1, sensor 1 (1-3 header, pre cat)

band 2 sensor 1, (4-6 header, pre cat)

bank 1 sensor 2 (1-3 post cat)

bank 2 sensor 2 (4-6 post cat)




edit: the relay should be an orange one, if oem. it appears to be a stanard 4 prong relay, and the part number is 0 332 014 454. i'm trying to add pics/location later, but this should be enough to get you to id it.




df
 
#12 ·
Alright so I bought a couple more O2 sensors, also NGK per OEM spec. So now I will have 4 new O2 sensors (post cats were a waste of money, but that is my stupidity for not reading/thinking properly).

If the P0155 is still present... then it must be the DME. Because I can't find the damn relay for the life of me. I looked on some fuse diagrams and it says Fuse 3 being the O2 heater relay... but doesn't say OBD1 or OBD2 car. If the P0155 comes back after I replace the two header O2 sensors, then I may just take it to the dealer for diagnostics. If they say new DME... I'll get it from one of the salvage yards here in my area and have it reprogged for $100 for my car.

I still don't see any severed wires anywhere or connections being loose or any burnt/shorted marks on the connectors.
 
#13 ·
Alright, replaced the two O2 sensors on the header, CEL is gone. The old Bosch ones that were removed looked VERY clean and nearly new (well being only 1 year old). I decided to keep one of them and toss the other one. I tested the resistance and came back at 5 ohms. So something was broken in there. I lifted the sleeve on the sensor and didn't see anything broken in the wires or the coating. Maybe it was just a defective unit. But hey, at least I have one good O2 sensor to play with now.

Somehow a part of me is still thinking the CEL may come back. I will hook up the reader to it and see if there is any pending codes. Hopefully there aren't any.
 
#14 ·
Harry, even with new O2s you might get a code in the first 100 miles of so of driving. When I replaced mine the CEL went away but came back on the next day. A BMW Tech acquaintance of mine told me give it a week or so and if the CEL is still on then start trouble shooting. At the beginning of the 2nd week the CEL went away and the O2 codes never came back. His theory is the O2 sensors drift a bit when they see the first 6-12 heat/cool cycles but once they settle in you're golden.
 
#15 ·
Is that on an OBD 1 or 2 car? Because O2 sensors have heaters built into them. I just don't understand the logic there from the tech.

Well, CEL is not coming back nor anything pending. I will relay what your tech said to my mechanic buddy and see what he says. :)
 
#16 · (Edited)
I just want to bump this for some information. I just got a P0155 code from my car too, right after I had exhaust work done. However, the headers which the O2 sensor is on, was untouched. I had a Bimmerworld y-pipe, 100 cell cat, and mufflers put on.

Using my Torque Pro app and bluetooth reading, I can get O2 sensor voltages. Reading my O2 sensor voltages, bank 2 precat stays at 0.98V constantly. Bank 1 precat fluctuates as the engine goes through its rev band. Is it pretty simple that my bank 2 precat sensor went bad?

Edit: Been reading about the fuses and relay for the heating circuit too. This doesn't make sense though, as only one bank is giving me issues, and there is just one fuse/relay for the entire circuit. The LTFT and STFT haven't shifted either. The max STFT I'm seeing is 5%, so it isn't a stuck open injector. Am I thinking right?
 
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