[Foxes]

Hey guys,

I need some help from someone well versed with the lambda sensors on our cars. The car in question is an 07 E92 335i.
I sent my car in for a service of my diff fluid, removal of rust and repaint of my diff and to fix my dented rim last week. Was going to collect her today when I got a call while at work that my lambda sensors had died. Those that feed from the cats. I found it quite odd that two could have failed at the same time and am attributing it to negligence. The workshop wants Me to pay for the new lambdas as they are saying that it failed prematurely. I just ended work and am heading cross border to collect her and talk out a deal with the supervisor. I am not going to pay this out of pocket if this was the fault of negligence and I would definitely not want to cause a mechanic to get his pay docked if this is truly a case of MTBF.

Please advice.

[weehe126]

I dont see how diff work could cause these to fail. Only way I could see it is if they removed the whole exhaust including downpipes to get to the diff. But that would be stupid as you can remove it after the dps, not touching the O2 sensors.

[Foxes]

Yes they removed the pipe, the mechanic was honest with the scope of works over the phone. How sensitive are they are how acceptable to damage are they? To add to the mix these sensors aren't cheap.

[335NJ]

Did they just get them switched around? If they removed them at all, they have to be put back in the correct pipe or they'll go crazy (Technical term).

[Foxes]

Sorry for the late reply, its been a long day. Collected the car last night, haven't payed yet as we came to an agreement that I would sit down with the mechanics and the boss to talk it over this coming week. They had changed a pair of brand new exhaust probes.

Anyway I noticed stronger than usual vibration resonating through the car the moment it started. It was immediate as I could feel the drivers seat vibrating. Fast forward today the car felt a little rough on mild acceleration and just highway cruising, similar to a shot guibo. Drove on and out of nowhere I hear this faint but noticeable hum from the engine as the RPM's hovered at 1500. Happened twice then the dreaded check engine light flashed on the dash. Tried restarting the car to clear the CEL to no avail, was still able to drive however I did notice that the engine would rumble noticeably if the RPM's went past 2000. Oddly enough though, a check on the control messages showed no faults.

Ended up driving the car home on what would be the most demure drive in awhile, never let the needle past 1500 for over 30 km.

I've contacted the shop and will be dropping her back again tomorrow for another round of works. My only concern would be that I would be seeing her on a flatbed before I can reach the shop.

[335NJ]

If this shop is involved in this much BS with the car, I'd go get another diagnosis/estimate from a different shop, and take the written diagnosis back to them.

[Foxes]

Yeah I am pretty much knee deep in this, I will go back this week and have a proper run through of what's going on and decide from there. Thanks NJ!