I have an 07 model trouble started with engine management ligh coming on this was showing B1 lambda sensor replaced this drove about two hundred miles and light back on had codes read same B1 sensor had sensor checked all reading ok. Had code cleared drove for another two hundred miles same fault. Took to nissan dealership they tested and said none of the sensors was reading as they should. Sensors should be giving out 2.3 volts but only 0.3 When nissan where testing abs and slip light came on and they can't reset they recon it is bad earth or cable anyone help car drives ok

 

i'm afraid i have no helpful input for your issue, but i have a similar one which maybe either yourself or someone else may be able to shed some light on:

i had the engine light come on after a fairly long trip, took it to the nearest garage to get the diagnostics which showed a problem with the lambda and knock sensor, the guy wiped the codes and the light hasn't come back on yet (it's been about 3 months).

had a google recently to find out what they actually were (cuz i'd completely forgotten about the problem since my trip and i'm mechanically retarded):

- lambda sensor is supposedly to do with emissions and fuel economy, but i haven't noticed any severe drop in average mpg

- knock sensor is something to do with managing fuel/air intake and having a damaged one can therefore put the car into a kind of safety mode which limits performance. i don't know if it's just in my head but it doesn't seem to be accelerating as well as it used to

(correct me if i'm wrong on those assumptions btw)

my question is this basically: if the engine light hasn't come back on, does it mean there isn't an issue or should i replace these asap?

it's an '03 model 350z (UK)

 

Your bank 1 pre-cat sensors should both read about .3-.6 at idle, and should fluctuate constantly between about .3 and .8 while driving.....approximately! A constant .3 means it's most likely toast.
The downstream catalyst monitors should read about .280 ish.
I would definitely be looking into some grounding issues, but how about telling us the code number for your specific code.

 

Lambda sensor is just a fancy term for oxygen sensor, although not exactly the same thing. It controls your fuel air mixture.
The knock sensor listens for that "cheap gas pinging" sound and retards the timing if it happens to hear the sound of pre-ignition or detonation. A broken one will keep your engine's timing pulled back to keep it from blowing up. You should notice that it has much less low-end power than it had before.

 

It does seem weaker between the 1k - 3k rpm ranges so should prob get these replaced. i don't recall the codes unfortunately, cheers for the response tho!