Technical O2 sensors petrol engine

[GrahamHM]

So, my 2001 Multi with a petrol engine is throwing up error codes - P0130 and P0141. These are listed as bank 1 sensor 1 and bank 1 sensor 2. (I haven't got around to the V8 upgrade yet!)

I can see sensor 1, it's sticking out of the manifold. But the current problem is sensor 2. The car is stalling in car parks and generally idling around the 650-700 mark.

I've just been under the car with a torch, and I absolutely cannot see any sign of the second sensor. I've got the sensor, a 22m spanner and even a specialist socket with a cut-out for the cable.

Anyone know where the blasted thing is, or even if there is one?

Thanks

Graham

 

[widemouthfrog]

Have you got the part numbers for the two sensors?

I've got little knowledge of the 1.6 petrol, but a quick look on ePER shows what Fiat call a 'sending unit' on or about the inlet manifold (71718678) and another on what looks like it could be a thermostat housing? (46520384, for Euro2 or 46753479 for Euro3 engines).

 

[GrahamHM]

So, I spent a few hours swearing at the EPR and looking through the CD based manual that I got a while back from Ebay. Me and the 15 year old, middle son went out there and had a poke around under the bonnet. As there is precious little info on the web about this particular car and engine combo I thought I'd detail everything on here.

We started off by identifying this connector as a likely candidate for the O2 sensor. It's on the drivers side of the engine bay, towards the screen.

IMG_20190915_181445627 by Graham Miller, on Flickr

Given that we had a rough location we jacked up the car by the right wheel and chocked and axle-standed it. Then, we followed the wire down between the engine and the bulkhead. I jiggled the wire from the top while the boy lay underneath to see where it led. Eventually we found that it led to a sensor on the exhaust. We'd previously lain underneath the car to find the sensor so we knew that it wasn't anywhere on the main run of the exhaust. We actually found it tucked up the vertical part of the exhaust between the engine and the bulkhead.

IMG_20190915_181553612 by Graham Miller, on Flickr

To find it we had to go in from the front corner, right under the engine and find the exhaust running down. The sensor was really tough to undo, I put a 22mm spanner on it and used WD40 and it was hot. Even with all that it was a pig to shift. Finally we got it, and then it was a question of winding the new one in (again annoying because the cable twists up and tries to undo it as you're putting it in).

We got the spare sensor from Ebay, quite cheap. And Halfords will sell you a sensor socket which is 22mm with a cutout for the wire. If you look closely in the top photo, the wire on the new sensor was a lot longer so we coiled it and cable-tied it out of the way.

Hope this helps someone somewhere!

Grhaam