Lambda Sensor Error and replacement

[MartinThorn]

'Morning! Over the last few months the engine warning light was coming on and then off again.. then eventually went permanent two weeks ago. The fault code that I'd already scanned via OBDeleven was P223700 which is the bank 1, sensor1 oxygen sensor, otherwise known as the Lambda sensor.

This is the pre-cat sensor that is at the back of the engine bay where the exhaust leaves the engine block.

I ordered this Bosch part 0281004191 from eBay which has a lead length of 660mm which is ok for my car (Mk3 Leon 2.0TDi FR184) for about £75 and today I finally got around to putting the new part in!

[Interestingly, the lack of working sensor did not seem to significantly affect the running of the car.. still seemed to have all/most of its power?! Anyway, engine warning light means MOT failure so had to be fixed]

Some photos following this post:

 

[MartinThorn]

The location of the sensor to be replaced was, like I said above, at the back of the engine bay and is quite easily accessible.

First I undid the small thermal blanket just below the circled area above which allows you to separate the O2 sensor cable from the other two nearby cable harnesses that are unrelated.

Then I used the special socket tool (another few quid) and my long breaker bar to get the old sensor out. I've heard stories about them being stuck in, but this one didn't take much force at all to get loose.

 

[MartinThorn]

Next was to undo the connector at the other end of the O2 sensor harness, then snipped off the connector so I could just pull the old o2 sensor harness through the various cable ties and that was it - sensor and its cable out in a few minutes.

It's not often that jobs go this smoothly so I allowed myself a few minutes of smug satisfaction!!

It definitely was knackered - can you spot which one came out of the car!

Anyway popped the new one in, gave it some torque (but not excessive amounts, might need to come out in 100k miles if I still have it!!) and job done.

Engine light self extinguished so didn't have to use OBDeleven to clear it.

Here's the other end of the old cable with the connector that I snipped off..

Not a terribly exciting thread, but as I had pictures I thought I'd share.

Easy job (if the sensor comes out ok), far easier than doing the heater matrix!!

Oh - this is the socket tool I used that helps get it in and out: ok, worked but the slot of this exact one is a bit narrower than it should be (chafes the harness outer sheath which no one really wants ideally!)

 

[MartinThorn]

Bonus pics of new vs. old O2 sensor.. This is hopefully only looking like that because it has done over 100k miles!