[mistryn]

I have been getting the following error code 4207 which points to a Lamda sensor heating so I presume the 02 sensor is faulty. Now my mpg has dropped significantly to low 20's and I think its due to this sensor being faulty.

I have scanned for codes and the above is the only one that comes up even after being cleared.

I have managed to source a 2nd hand sensor with low miles and want to swap mine over. Luckily on the 35d engine there is only one 02 sensor but the access is limited.

I would like to have a try myself but do I need a special 02 removal tool. My main concern is it being siezed on and it snapping off. Is it best with the engine warm?
Also I have noticed the new sensor have some sort of grease applied, as mine is 2nd hand should I used any grease on the threads, if so which type?

Also I want to give the sensor a clean what shoudl I use?

Or should I leave it to the garage?

[mistryn]

Anyone??

[makkan00]

Originally Posted by mistryn

Anyone??

Can you post a photo with its location?

[mistryn]

I will post a pic up later tonight

[mistryn]

Thought I would update this thread just in case if anyone else is looking to replace this. My initial thoughts would be an hour to change, I was slightly wrong took me 2 and half hours as more things needed to be removed.

Problem – fault code 4207 – Heating sensor element – symptoms poor running in the morning and MPG dropped to low 20’s and high teens

1 O2 sensor (I bought a low miles second hand one)
22mm O2 sensor socket removal tool
Socket set including torx bits/breaker bar for leverage
Halfords Shock and unlock (to use on seized nut)
Anti seize grease

Will need to remove engine cover, mircofilter cover, bulkhead cover, airbox and air intake.

The O2 sensor is located just below the big turbo by the silver protective shield. I sprayed shock and unlock as mine was seized after 113k miles – Shock and unlock sprayed left for 30 seconds and sensor came off with ease with long breaker bar. Reason why I removed air box was to get more leverage

The wiring (this is the longest part it took me) runs from the sensor, underneath the pressure converters and up and behind the pressure converters. However BMW in their wisdom decided to cable tie the wire under the pressure converter so could not get cutters in. As a result I had to unbolt the PC bracket by 4 bolts, remove a couple of connectors to the PC and cut the cable tie to loosen the wire. The strut bar also had to be removed.

Fitting is reverse, I applied small amount of anti seize grease, hand tight the sensor (did not have my torque wrench with me)

Car runs a lot better and my mpg has returned back to normal and no fault code

Couple of pics along the way as I was pushed for time

[makkan00]

Respect for doing all that. I'd have taken it to BMW specialist.

[rogerdiaz]

So replacing the O2 sensor is a straight swap? No other parts required?

[mistryn]

Yes straight swap, will need the deep cut out socket and anti seize compound to help next time round should you need to remove it

[rogerdiaz]

Originally Posted by mistryn

Yes straight swap, will need the deep cut out socket and anti seize compound to help next time round should you need to remove it

How many oxygen sensors to replace? I have a u.s. 335d sedan.

[mistryn]

I presume us has the same as UK which I just the 1 02 sensor