BMW Z3 3.0i (M54) – Post-cat lambda heater fault + live data

[hawky443]

Hi all,

I’m looking for some confirmation on the correct post-cat lambda sensor for my Z3 3.0i (M54), as I’m seeing conflicting part numbers.


Car:
2001 Z3 3.0i, M54, UK spec, auto


Fault code (Carly):
Insufficient heat output – oxygen sensor after cat – Bank 2
Fault won’t clear.


Symptoms:

• Engine runs well since replacing the exhaust cam sensor
• MPG improved
• On cold start there’s slight idle hunting for the first minute, then it settles
• No misfires

Live data (Carly):

• Pre-cat lambdas switch normally (about 0.1–0.8 V), heaters active
• Post-cat lambda sits around 0.44–0.46 V, very slow/no response to throttle

Wiring looks OK and this is the only remaining fault.
From what I can tell, this points to a failed heater in the post-cat lambda sensor, but I’m stuck on part numbers.

BMW diagrams list sensors like:

• 11781739845
• 11781742051

However, I’ve also been told the correct OEM part for the post-cat sensor on the M54 is:

• 11787530282 (11 78 7 530 282)

That number doesn’t always show up in the diagrams, which is confusing.

Questions:

1. What is the correct OEM part number for the post-cat lambda on a Z3 3.0i M54?
2. Are the other numbers for different emissions specs?
3. Is Bosch / NGK / NTK / Vemo OK for this position?

Any advice from someone who’s replaced this sensor on an M54 Z3 would be much appreciated.


Thanks.

 

[NZ00Z3]

www.RealOEM is your friend here.

Where in the exhaust system are your cats mounted? I'm picking, right at the exhaust manifold, so 11781433940 is your sensor. Yes, that's another number, this one is from RealOEM. Go to that web site and put the last 7 digits of your VIN into the search tool and browse for the right part number for your car.

• 11781739845 is for a car with the cats 1/2 way down the exhaust system, Long lead
• 11781742051 is for a car with the cats 1/2 way down the exhaust system, Short lead
• 11787530282 is for the E90's
• 11781433940 is for a car with cats right at the exhaust manifold.
  
  
  
  
  
  
  
  

 

[hawky443]

www.RealOEM is your friend here.

Where in the exhaust system are your cats mounted? I'm picking, right at the exhaust manifold, so 11781433940 is your sensor. Yes, that's another number, this one is from RealOEM. Go to that web site and put the last 7 digits of your VIN into the search tool and browse for the right part number for your car.

• 11781739845 is for a car with the cats 1/2 way down the exhaust system, Long lead
• 11781742051 is for a car with the cats 1/2 way down the exhaust system, Short lead
• 11787530282 is for the E90's
• 11781433940 is for a car with cats right at the exhaust manifold.
  
  
  
  
  
  
  

ive looked there however it says no information

 

[Lee]

Normally the M54 has a set of 4, 2 post 2 Pre. Stick your head under to confirm the post sensors should be about an inch back from the flange.

Re the sensor sounds like the internal heater has failed, funny enough I have the same issue on my car and waiting for a replacement.