Welcome to our resource for MG Car Information.



MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGF Technical - MGF cat converter worries

I hope someone can help.

I own a cherished 1998 MGF 1.8i. I've recently purchased a new cat converter for my car and took it down to my mg specialist for fitment.

The specialist claims that my old cat has a sensor on/in it and the new one doesn't. The supplier claims the sensor is located in the "down pipe" and not on the cat.

The specialist also claims that some F's had 2 sensors and some just one? ...mine apparently have 2!

Is there someone out there that can shed some light on this? Why will one car (the F) have 2 different cat configurations?

Thanks in advance

PJ Pienaar

Re-imports from Japan perhaps!
Ted Newman

Two possiblities:

1: A jap import has an overheat sensor, this is not needed in the UK, but I don't know if the ECU uses the info.

2: Later cars have a Lamda sensor before and after the cat - early cars like your own should have only one sensor in the downpipe.
Will Munns

Ted, Will

Thanks for your prompt replies!

Yes, my car is indeed a Jap re-import! Well diagnosed!

Does anyone know if the ECU uses this info as mentioned by Will?


PJ Pienaar

It is used to illuminate a warning light on the dash. Nothing else. Either tape the sensor up out of the way where it'll never overheat, or remove it and then also remove the bulb from the dash. I'd just tape it myself.

Paul Nothard

See the Archives and here at
Dieter K.

The the cat over heat is a fuseable link - but I don't know exactly where it's positioned: I've never seen one - but being in the down pipe is a surprise!!!

There is one Lambda sensor in the exhaust manifold, and on EU3 cars registered after 2001, there is a second Lambda AFTER the catalyst. What you're describing doesn't seem to be either of these, so it would seem to be the over heat sensor.

When you remove the sensor and replace the cat (without sensor), it will cause the lamp to illuminate: the warning lamp comes on when the circuit is broken. Therefore when you replace the cat, ground the brown/black wire to the chassis.

Rob Bell

Rob, Dieter and Paul

Your advice is invaluable! Thanks you very much. I'll relay the information to my mechanic.

Kind regards

Philip Pienaar
PJ Pienaar

This thread was discussed between 18/02/2005 and 19/02/2005

MG MGF Technical index

This thread is from the archive. The Live MG MGF Technical BBS is active now.