Cat By-Pass exhaust - but what do I do with the Lambda Sensor

Car - 1.6  Mk1 1993 Eunos,
I Bought a full Stainless steel exhaust with a cat bypass(MX5 Parts-QS201), but I have a Lambda Sensor in the cat.
 What do I need to do with the sensor or wires to make sure the car still runs smooth?
My Cat By-pass pipe dopes not have a sensor mount.
any help out there ?

 It isn’t a Lambda sensor, it is a heat probe only required for the Jap market.
Either tie it up as I have done, or pull the loom (there is a clip under there)
You will have no ill effects, it doesn’t send any info to the engine, it just lights up a dash light if it overheats and then the probe needs to be replaced anyway.

Are you sure its a lamda sensor? My 1991 Eunos had a temp sensor on the cat that I just unplugged and left off.

The temp sensor triggers the light that says ‘heat’ on the dash I think. I was told that unplugging can make the light stay on but mine hasn’t.

-I could be wrong though, anybody else?..

As halli says It’s just a heat sensor.Tie it out of the way or unplug it from the loom if you can find the joint. Will not keep the heat light on------------------

 Excellent many thanks, now just got to wait for the temperature to go above -5C !!!

 I plan to fit the MX5 Parts s/s exhaust this weekend and was checking out the forum for tips when I found this thread. My Haynes manual says that some models are equiped with an additional oxygen sensor mounted in the exhaust system after the cat, in order to provide a comparison reading with the other oxygen sensor mounted in the manifold. Surely removing this cat-mounted sensor will render this comparison reading inaccurate?
Having said that, the manual also states that outside certain temperature ranges it will fall back to a default reading for emission control purposes, so I guess this is what would happen 100% of the time if the cat sensor is removed?

Whatever, nobody seems to have reported any problems in removing/disabling this cat sensor so I guess I’ll just go ahead and zap it…!

It is just a switch, not a sensor. Either remove the loom or tie it up to the PPF. It has a clip conector so is easy to remove.


(ever think you are repeating yourself? ;) )

Later models did get a second lambda sensor to check the operation of the cat, as described above, but if the car’s a Mk.1 then it definitely didn’t come with a second lambda
sensor.  If it’s a Mk.1 Roadster then it will have a heat sensor.

 OK, so its a heat sensor, and its about to be disabled…!

Thanks for the advice folks.