rear oxygen sensor, where is it?

alizarin09 · Post by **alizarin09** » 26 Dec 2009, 19:03

2001 S40
I need to replace the rear oxygen sensor and I wish I had a diagram or photo or something to show me where it is and how to replace it. Thanks!

Post by **billofdurham** » 27 Dec 2009, 12:34

Welcome to Matthew's Volvo Site.

Both heated oxygen sensors are in the catalytic converter. The front sensor is at the top and the rear sensor is, would you believe, at the bottom.

The attachment shows how to remove the rear sensor. "Lambda Sonde" was the original name for the heated oxygen sensor.

S40 Rear HO2S.pdf: (1.63 MiB) Downloaded 1494 times

Bill.

alizarin09 · Post by **alizarin09** » 27 Dec 2009, 19:01

THANK YOU!!!

Just a couple of questions though (I'm new at this, I've only ever changed simple things like filters and bulbs) what part of the car am I looking at? i.e. where is the relay cover, is it under the hood or under the car by the tail pipe? and what is 55Nm, do I need a torque wrench? Thanks again.

keithatcpt · Post by **keithatcpt** » 28 Dec 2009, 08:46

On my 2000 S40, the relay cover where the oxygen sensor plugs into is under the hood at the top of the firewall. I used a 3/8" drive breaker bar and a 6" extension with a 22mm "crowsfoot wrench" to get the thing out. Open the hood and reach down behind the catalytic converter to get to the sensor. Make sure you remove the sensor AFTER the catalytic converter if you are removing the REAR sensor.

You might want to spray some Liquid Wrench on the threads a few times before you start and let it soak.

Make sure the engine is BONE COLD when you spray the Liquid Wrench or when you reach behind the catalytic converter.

- Keith

alizarin09 · Post by **alizarin09** » 01 Jan 2010, 18:53

Thank you. I hope it is the same for a 2001.