slow down light

Different ECUs for those failures. You can download a 550 workshop manual for free from ferraridatabase.com and it should help on the ECUs. 550 owners will chime in soon on how to diagnose by swapping ECUs side to side to see if the problem migrates.

 

Whoops, you are correct. I was thinking there was a slow down light for each bank. Must be another model. There is a WSM index on the left side of the document. If yours does not have it, suggest downloading one that does.

 

I had the exact same problem a few days ago. Basically there is a sensor that monitors the temperatures for each cat that will throw the slow down sensor if either side detects a cat temp in excess of I think 1200 degrees F. If you drive the car it will cripple one bank and you will experience a severe loss of power. Replacing the component (approx. $380 for the part) should fix the problem.

 

Have a look at the Workshop Manual, Volume 1, C38.
The slow down light is normally caused by a faulty thermocouple (13 in the diagram) or its control unit (7).
Check units 7 to make sure the connectors are properly attached, and make sure they haven't cracked open due to heat in the engine compartment.

Stefano

 

My experience with cold-start slow-down warnings has been bad thermo-couples. Does the light go off after you begin to drive and everything heats up good? If so, once again... replacing the thermo-couples resolved this symptom "for me".

It seems that the thermo-couples also need to see a certain amount of flow. If they are old, or fouled... causing them to not get a good read when exhaust flow is slower, they throw an error, but you never lose one bank or the other. Driving, like on the highway, eventually heats them up and gives them more flow at which point they can actually measure temps, making the indicator go out.

This is no guarantee, but this was the fix for my cold start errors that would go away once I started driving.

 

Years ago mine came on, I just reset it and never seen it back. I just done it with basic OBD II. It won't hurt to try.
Sark

 

Same problem. Had to replace both ECUs and thermocouplers. No problems after that. If I could have diagnosed the problem, I would have done the work myself as it's quite straightforward. Frank

 

If I remember correctly, I think someone on FerrariChat said there was a company (perhaps in England?) that rebuilds the ECUs at a greatly discounted price from list. Sorry I can't recall more. Frank

 

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You're welcome.

Three years ago, I got an intermittent SLOW DOWN light which soon became continuous. It was a bad thermocouple for the right bank.

 

Eurospares UK has the CAT ECUs for a lower price than US sources

 

I had both CEL and Slow Down lights on my '95 456GT.

Installation of the SRI gold pin connector kit banished them, hopefully forever.

 

same problem ( référence Ferrari 179278 )

 

That's great to hear. The error code will ultimately clear. You might get repeated SLOW DOWN lights until you cycle the car on and off several times and drive 50 miles or so.

 

Just got this message yesterday. I drove back to the parking place and today the message appears right after start up (so an actual overheating is very unlikely). I will try to have a fix next week, asking both the indy that sold me the car and Ferrari.
The thermocouplers are ref 174674 and the ECU number I found on eurospares is 179278; thermocouplers are cheaper than ECUs.

 

Inexpensive aftermarket ECUs and "universal" thermocouples are now available at Technistrada...

https://technistrada.com/

Be sure to pick the longer thermocouples for the 550/575

 

Most of us end up changing out the thermocouples as they get marginal. I did and unluckily before Technistrada had these available.

 

The out-of-state shop that did the PPI and a bunch of work on the 550 I just purchased, replaced the left-side ECU and everything was good. Now that I have the car, I'm seeing the flashing Slow Down light (happens on cold start, no misfire, car runs great) so they recommend I change out the right one. Would it be a problem to mix what I'll call a "stock" version (left-side) with the "improved" version from Technistrada? Thanks.

 

No difference they can be mixed, the technistrada ones are better quality, but the electronics have the exact same function as OEM.

 

So I got my Technistrada ECU and installed it. Should the Slow Down light just stop flashing or is there something that needs to be done to clear it? Thanks.