MOT high CO emissions

[Ardent]

In the cat. Left side.

Unless import in which case ignore the above.

Might need to remove the nappy. Cannot remember as no longer have one.

[Joesson]

@fawtytoo

The 3rd sensor, assuming a standard single exit OE exhaust is on the Left side of the back box on the exhaust pipe. I guess a TTE dual exit would be in the same position.
Difficult to see from above but get down and look under the rear "bumper".
This sensor has a longer cable than the others, I've only replaced that once and the new long cable can be a fiddle to get it where you want it. My sensor was dead and so I cut the cable close to the sensor, that allows an alternative, regular socket, or ring spanner,to get into the limited space.
I tied a cord to the cut cable end end, pulled it through to the connector point and used the cord to pull the new cable up to the connector.
Room for leverage is somewhat limited but with some easing fluid and patience mine came out. Not so much leverage to replace and not forgetting a dab of Copaslip  on the back end of the thread, NOT on the business end.

[Pete McCue]

@fawtytoo

The 3rd sensor, assuming a standard single exit OE exhaust is on the Left side of the back box on the exhaust pipe. I guess a TTE dual exit would be in the same position.
Difficult to see from above but get down and look under the rear "bumper".
This sensor has a longer cable than the others, I've only replaced that once and the new long cable can be a fiddle to get it where you want it. My sensor was dead and so I cut the cable close to the sensor, that allows an alternative, regular socket, or ring spanner,to get into the limited space.
I tied a cord to the cut cable end end, pulled it through to the connector point and used the cord to pull the new cable up to the connector.
Room for leverage is somewhat limited but with some easing fluid and patience mine came out. Not so much leverage to replace and not forgetting a dab of Copaslip  on the back end of the thread, NOT on the business end.

It's not on the tail pipe it's in the section of pipe after the cat but before the back box.

[Joesson]

It's not on the tail pipe it's in the section of pipe after the cat but before the back box.

Twelve years can blur the memory!

[Ardent]

It's not on the tail pipe it's in the section of pipe after the cat but before the back box.

That's the one.

[Ardent]

If buying an oem denso. It also comes with clips correctly spaced along the cable that locate into the dedicated holes in the frame. Just push ins. I found that satisfying. The cable could go a few ways. But you will know when it follows the path intended by Mr T as the clips will just happen to fall at a locating hole. Nice.

[BahnStormer]

I bought one but where is the 3rd sensor? Is it on/near the cat? Do I need to remove anything to get to it?

Third sensor is accessed from under the car... just look at the exhaust tip and work your way back up - won't have to go too far.... if it's an MR-S, it only has two, but the EU spec ones all had three.

[Carolyn]

You need to remove the passenger side tail light to get at the connector.