Oxygen sensor replacement

[keithyboy]

Using the excellent torque android app and a bluetooth OBDII reader, I've established that there's a fault in the front O2 sensor heater circuit on our '03 1.8 (122bhp Volvo engine) which I think means a new sensor.

I had a look underneath today primarily to establish how many wires and their colours (4, red, white, black yellow as it happens) to make sure I get the correct replacement part. I was expecting to see the wiring head in the general direction of the engine bay wiring look so was surprised to see that it disappears through a grommet in the floor into the cabin.

The big question is where does it go next and where is there a multi-pin to undo? Do I have to take the console out?

Any and all advice gratefully received.

[gatos]

If you pull out that grommet gently, it will come off. Pull the wiring out 2-3 inches and you will see a connector. There is enough loom for you to pull the connector out of the hole and you just unplug it and plug in the new lambda

[keithyboy]

Originally Posted by gatos

If you pull out that grommet gently, it will come off. Pull the wiring out 2-3 inches and you will see a connector. There is enough loom for you to pull the connector out of the hole and you just unplug it and plug in the new lambda

Brilliant. You're a star.

[dcw]

Hold on - I may be getting confused here, but you said front O2 sensor. The sensor with the wiring that goes up into the cabin is the rear O2 sensor.

Gatos is absolutely right about how you get at that one (wouldn't expect anything less!) but if you really mean the front sensor it's way up in the downpipe at the back of the engine compartment.

If you look down onto the exhaust downpipe you can see the sensor screwed in, and its wiring runs (in a yellow on black sleeve) up into the plastic box which sits centre rear of the engine compartment just in front of the scuttle panel and its rubber seal. Remove the black plastic cover and unplug the connector - it's the one at the left hand end.

Doddle to change - recommend using genuine Volvo or Bosch (who make the genuine Volvo one, complete with "Volvo" stamped on the connector plug).

David

[gatos]

DCW is absolutely correct. I didn't notice that you said front Lamba. If you have the 1.8 Volvo engine, then the front lambda sensor does not go inside the passengers compartment. Instead it connects at the top middle of the bulkhead

However, if by any chance you have the GDI engine then there are 3 bits with wiring connected to the exhaust. So maybe you are confusing the middle sensor with wiring, to be the front one. I have a complete set of Lambda sensors for a GDI in case you are interested to try them on your car and see if they solve your problem

[960kg]

I believe the above by Gatos is for Phase 2 but just in case some of you have Phase 1 this was my "How To" back in June 2009.

http://www.30forty50.com/forum/topic...sensor-in-cat/

It may help?

[keithyboy]

I've just been out for a look. Admittedly it's quite dark out there but I did have a very bright light and I cannot see any sort of sensor or wiring on the downpipe. I took the plastic cover off the bulkhead and there are two rectangular plus under it, the wiring for both of them goes into the wiring loom.

To clarify, am I looking from above or below and from which side am I best looking?

[gatos]

Could you please let us know which engine you have? The 1.8 Volvo one or the 1.8i GDI Mitsubishi one?

[keithyboy]

Originally Posted by gatos

Could you please let us know which engine you have? The 1.8 Volvo one or the 1.8i GDI Mitsubishi one?

Volvo engine. The car is an '03 plate.

[gatos]

In that case, I think both front and rear lambda sensors are within a few inches on either side of the CAT. Easiest way to access them would be from under the car