Hello all.

Just after some general feedback on a few things.

I have a 2005 Mitsubishi 380 VRX manual transmission which has done 190,000km. It has been a great car and have had it from new.

My yellow engine tuning check light on the dash recently switched on. After some diagnostic work I found error code P0421 Catalyst system efficiency (bank 1) too low. With some further diagnostic work and checking the post cat oxygen sensors were all over the place on both banks which is highly indicative of catalytic converters not working correctly. So my general questions are:

1) Peoples experience on replacing cats on 380? Ease of doing?

2) Similar issues with vehicles of similar mileage?

3) Recommendations on cats, genuine or aftermarket?

4) Recommended place to buy?

Any feedback would be much appreciated. Thanks in advance.
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Whens the last time the O2 sensors were checked and/or changed?
Any chance it could just be the sensors on the way out, rather than the catalytic converters?..

Changed all 4 O2 sensors 10000km ago. Also checked them on oscilloscope and signals responding well..so they are ok. Thanks

The 380 pre-cats are integrated into the exhaust manifolds, so big bucks to renew.
The third cat is just a dummy, a white brick, so replacing it won't achieve anything.
Only other solution is to replace the exhaust manifolds with extractors and the third cat with a real one.
I did this but I wouldn't recommend it as the only extractors you can get for a 380 are RPW and they aren't very good.
Prone to cracking and rattling.
Also, you will still get CELs and O2 sensor error codes (just different ones to P0421), although the codes are harmless.
I covered the CEL globe in the cluster with a piece of black felt.

As TreeAdey has mentioned, the cats are part of the manifolds. If they are the problem, you may be better off getting a pair of the manifolds from a wrecked 380 with lowish kms, and getting them fitted. The labour is going to be costly either way unless you have the time/equipment to do it yourself. If you want new items, I don't know if there are many options available other than from the dealer. I know the list price on the US equivalents (ie. manifolds including the CC) was around $500 each when I was doing some research... so not going to be cheap.

Go to an exhaust place, get them to cut and chop/weld the stock manifolds and replace them with metal ones.

best way to get it renewed in my humble opinion.

Thanks for all the feedback guys..yes a. Costly exercise..new items are around $1200 each! Good second hand ones around $250 ea plus fitting..may have a go myself. The front bank looks ok. The rear bank looks like a bit of a pain though. Will also get an exhaust fitter's suggestions as well. Cheers