My Ferrari 360 was flashing a SLOW DOWN light after driving it for more than about 30 minutes, so once the car was up to operating temperature. According to this post by Adlous Voice, a likely cause of this issue is the catalytic converter temperature control system, which some people call the Cat ECU. Basically, there is a small part with some logic in it that monitors the temp going in and out of your catalytic converter, and if something looks wrong it’ll show a SLOW DOWN light on your dash, and possibly reduce power.

The original Cat ECU from Ferrari is known to be overly restrictive, and prone to failure, so a company called Technistrada out of New Zealand makes a upgraded part, sold here. The idea is that you have 2 Cat ECUs, one for each side of your exhaust, and likely only one of them has gone bad. So replace one side, if the SLOW DOWN issue goes away, you’re good. If it doesn’t go away, you likely just replaced a good part, so put that good part back on, and swap the bad part on the other side of your exhaust to the Technistrada part. That’s what I did, and I got it right on the first time.

Here is the new part vs the old Ferrari OEM part

To install, remove the protective covers from one side of your engine. I did the right/passenger side first, which was the correct side. You can find out exactly which side is causing issues if you have a $10k Ferrari scan tool. I did not. I was also not able to fully remove the largest engine cover, but I was able to slide it out of the way to reach the part for replacement.

There are quite a few 4mm hex/allen screws to remove. Mine even had a T-25 torx screw, which might be not supposed to be there.

The screws to remove the old Cat ECU are 7mm bolts, I was able to get a ratchet with an extension in there. It’s a tight squeeze.

Once that’s out, swap the plugs like for like, there are only 2 different plugs so that is easy. Re-attach, turn the battery on and do the 10 minute warmup procedure (run the car 10 minutes at idle), then drive it. I left my engine covers off for about a month just to confirm I replaced the correct side before re-assembling.

That’s it! Now I have no SLOW DOWN light and I feel more confident driving my 2001 Ferrari 360 Spider around.