F40 problem

I have seen a lot of people on this forum ignore the "slow down" light and try to pretend that it does not exist. This could cause a serious problem. About three years ago the same thing happened to me and I tried to pull over immediately. By the time that I did, the back end of my car was on fire. It seems that I had lost one of my ignition coils and was dumping fuel into my cat on the right side. The flames coming out of my exhaust melted the rear bumper(US Model) and the rubber started a fire. F40's foul plugs quite easily. If this occurs, a fire in the cat will ignite. The "slow down" light signal comes from a thermocouple in the cat that warns of overheating. Do not disregard the warning light. Take it to your mechanic or the dealer for evaluation. I was lucky that I had just installed an on board fire extinguisher and had another one under my seat. look to see if your cat is discolored compared to the other side . My guess is that the cat will need replacement.

 

Is an F-40 like a 348?

The sensor could be right- the cat is overheating.

But if the temp is fine you could have a bad ECU. Or possibly a bad temp sensor or O2 sensor.

But you say it occours on both sides. Seems odd to loose both sides at the same time. Maybe a bad ground point for the sensors?

 

You might want to try swapping the two thermocouples on each cat and see if the problems "switch sides". (Part #34 in below picture) If they do, the problem is the thermocouple, not the cat.

Having said that, if you really believe the cats are overheating (are they glowing red?), just take the car to a qualified mechanic.
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