P0155 Code Help

[m3f_RND1]

Recently completed clutch job and everything went back together smoothly. No CEL's before job, but CEL immediately on first fire up. Code P0155 indicates O2 Sensor heater element, bank 2, sensor 1. My car is a 6/98 build and it seems some changes were made after 4/98.



I'm trying to figure out if this is a pre-cat sensor or post-cat sensor? I didn't touch the pre-cat sensors, but did get some antiseize on the post cat sensors while reinstalling. Wiped off as much as possible with a rag, no solvent. Figured it would burn off. Any help greatly appreciated - due for inspection this month and won't pass with CEL on.

[m3f_englishtom1596q]

bank 2 is the back 3 cylinders and sensor 1 is precat. someone correct me if I'm wrong but thats what i was told. i have the exact same code after i replaced my clutch too. all i could think of was maybe i banged the pipe hard enough to break the element when reinstalling my exhaust... I've yet to replace the sensor since its $120 ish part

[m3f_RND1]

bank 2 is the back 3 cylinders and sensor 1 is precat. someone correct me if I'm wrong but thats what i was told. i have the exact same code after i replaced my clutch too. all i could think of was maybe i banged the pipe hard enough to break the element when reinstalling my exhaust... I've yet to replace the sensor since its $120 ish part

Thanks Tom. I did have to bang out a broken exhaust flange stud so maybe that's what killed the heater element? I'm going to replace both pre-cat sensors with the NGK sensors from Amazon today so I'll let you know if it works.

[m3f_englishtom1596q]

sounds like a plan. i was looking at just doing both of mine as preventive maintenance when I've got the cash. I've still been averaging 27mpg freeway with the check engine light on so I'm not complaining.

[m3f_RND1]

sounds like a plan. i was looking at just doing both of mine as preventive maintenance when I've got the cash. I've still been averaging 27mpg freeway with the check engine light on so I'm not complaining.

I can't pass inspection in MA with the CEL on so I don't have a choice. It's running fine and gas mileage is respectable considering the M is mostly used for spirited back road touring.

[m3f_white-hot]

I've yet to replace the sensor since its $120 ish part

They are <$60 each on Amazon. Just sayin....


Amazon.com: NGK 25013 Oxygen Sensor - NGK/NTK Packaging: Automotive




Amazon.com: NGK 25013 Oxygen Sensor - NGK/NTK Packaging: Automotive

[m3f_englishtom1596q]

you are a damn life saver! thanks

[m3f_white-hot]

&#91;Smilie: Beer&#93;

[m3f_Wazmo]

Are those plug and play? Or do you have to cut the wires and such? I have to do these and have been staying away due to price as well.

[m3f_white-hot]

The 25013 is the one for our cars, so yes.

[m3f_Wazmo]

Cool. Thank you!! That is a huge help!

[m3f_BeerHat]

sounds like a plan. i was looking at just doing both of mine as preventive maintenance when I've got the cash. I've still been averaging 27mpg freeway with the check engine light on so I'm not complaining.

Yeah I would recommend doing both ASAP. I put mine off for a long time too, then a few weeks ago I broke one of my sensors doing my motor mounts, I figured it was time I just bit the bullet and did my two pre-cat sensors (ala 120 bux from amazon), at 92k.



Don't bother with the post-cat sensors unless they're throwing a code. They do nothing to tweak AFR, they're just there to throw idiot lights when the cats are bad. All 4 use the same part numbers, so you can swap them around if you need.



Anyway, the result??? It feels like a whole different beast now. No placebo effect going on here - it was easily the best bang for buck horsepower/torque gains I've ever felt on any car. Midrange is now back and 5th gear PUUUULLS again. That 2nd gear bark is much, much more pronounced. Here I was thinking I was just geting used to the power the last few years. Driving it now brings me back to the 'insane power band' I remembered from my very first test-drive.



Who would have thunk that a pair of failing sensors needs to be SO bad in order to throw a code. And there WAS NO CODE until idiot me broke one. And yes I was also getting 27mpg according to the trip computer. BTW, that thing's not exactly accurate, but it's close.



Dan

[m3f_RND1]

Anyway, the result??? It feels like a whole different beast now. No placebo effect going on here - it was easily the best bang for buck horsepower/torque gains I've ever felt on any car. Midrange is now back and 5th gear PUUUULLS again. That 2nd gear bark is much, much more pronounced. Here I was thinking I was just geting used to the power the last few years. Driving it now brings me back to the 'insane power band' I remembered from my very first test-drive.

Dan

This is interesting. My NGK sensors just showed up, but didn't get a chance to put them in this weekend. My M was off the road for a long time while I was doing the clutch overhaul and a bunch of other stuff, but since getting it back on the road (with cel) I've felt the powerband was not quite what I remembered. I too felt that I've just gotten used to the power, but maybe not? I'm excited to get these in now and get back to the "insane power band" that I remember! Hope I have the same experience.

[m3f_greyflyer]

Interesting. I've never seen 27mpg in any circumstance. Best I've gotten is 24-25mpg on a road trip, and I average 22mpg in my daily commute which is a mix of side roads, freeway and heavy traffic. Of course I do have an exhaust and can't keep my foot out of it.

[m3f_BeerHat]

Interesting. I've never seen 27mpg in any circumstance. Best I've gotten is 24-25mpg on a road trip, and I average 22mpg in my daily commute which is a mix of side roads, freeway and heavy traffic. Of course I do have an exhaust and can't keep my foot out of it.

With the high number of CHP in my area , cruise control is my friend. I'll usually dial it in around 70 and enjoy the scenery. Last weekend when I tripped it to disco bay (100 miles), the computer read 28mpg when I arrived. Straight shot all freeway, no traffic/stopping, didn't get on it at all. Not even once! Rare for me. I even had a heavy cooler full of beer, a Dell server, and miscellaneous camping/fishing essentials stuffed in the trunk.



Like I said, the computer lies a little bit, but hell even if it's close to close -- I'll take it!



Dan