w203 220cdi lambda/o2 sensor

[mrblubo]

Hi everyone
I have c220cdi '05 with little problem
engine runs OK, but time to time I check it with diagnostic reader
it comes out on my one as p2a00 - bank 1 o2 sensor
on BOSCH kts650 as -> P2073 Lambda sensor upstream of CAT.

only problem with the car - every other time I start it and drive it comes on the dashboard roughly 25mpg, when normal is around 45mpg on the same trip/ style driving.
as far as I know it is unusual on them engines to o2 sensor been faulty, even merc dealer says it maybe something different...

Can anyone help
cheers

 

[SteveFromAvantgarde]

Ideally you need to get it onto a star machine and see what live data you are getting in actual values. Also check the wiring to the sensor and see what gives there too.

Some of the scanners you mention are no help when trying to diagnose something like this. You need star.

 

[mrblubo]

thanks, but in my area nobody has a star, so I better check wiring and a plug - only MB dealer about 40 miles away- I work every day till 6 so will be hard to sort it out.
thanks anyway

 

[shishi426]

hello, my car is the same as yours, 54 reg, and has exactly the same issue.
did you solve the problem by replacing the O2 sensor?
thanks!