348 help

[hollywood]

i have recently purchased a 348 and have a warning light on the dash every once in a while. (slow down 5/8) any advice?

[CraigW]

probably the sensor, cant remember what its called. get it checked asap though & if you experience a bank of cylinders shutting down dont drive car.

[Siban]

Probably the Lambda sensor. I had both go on my 348 and it's a really easy job to replace. If you look down at the exhaust pipes where they come away from the exhaust manifolds, you'll see the two sensor's as they stick straight out from the top of the pipes. They just unscrew. You can swap them over and if the fault goes to the other bank then you know it's the sensor. You then just ring up Maranello and get them to ship you a new one and fit yourself.

[F355SPIDER]

hollywood said:

i have recently purchased a 348 and have a warning light on the dash every once in a while. (slow down 5/8) any advice?

Congrats on the car.
Quite common on 348 and 355. Youll find lots on this on ferrarichat.

[chrisx666]

The 348's cat convertors are fitted with thermocouple sensors that, via a small ECU, signal if the cat overheats. This flashes the 'slow down' indicator (one for each bank of cylinders). This is a different light to the check engine lamp that would come on for say a bad sensor.

Possible causes:

1. The cat is actually overheating. Very dangerous - car may catch fire.
2. Thermocouple is bad.
3. Cat ECU is bad.
4. Electrical connections on the above bad.

All are common. Try cleaning all the connections. Maybe swap the cat ECU's from side to side and see if the problem transfers.

[F355SPIDER]

chrisx666 said:

The 348's cat convertors are fitted with thermocouple sensors that, via a small ECU, signal if the cat overheats. This flashes the 'slow down' indicator (one for each bank of cylinders). This is a different light to the check engine lamp that would come on for say a bad sensor. Possible causes: 1. The cat is actually overheating. Very dangerous - car may catch fire. 2. Thermocouple is bad. 3. Cat ECU is bad. 4. Electrical connections on the above bad. All are common. Try cleaning all the connections. Maybe swap the cat ECU's from side to side and see if the problem transfers.

my light still comes on from time to time and dont even have any cats! its been tub de-cated.cant understand why.

[M6TT F]

This is the Thermocouple ECU or temperature probe in the Cat - 5/8 is the right bank (when stood at thr rear of the vehicle)

[F355GTS]

Cat ECU's are a common failure, the insulation breaks down and water gets in

[burriana]

F355SPIDER said:

my light still comes on from time to time and dont even have any cats! its been tub de-cated.cant understand why.

Taking the cats off does confuse the thermo-coupler sensor somewhat. Simply undo the plastic connection half way between sensor and ECU (attached to one of the struts). Has worked for countless people.

DO NOT DO THIS IF YOU STILL HAVE CATS!!! (simply remove cats then do it!)

[adi]

Just a warning - I had this problem on mine and one of the cats did indeed catch fire and spit flames out of the right bank pipes. Melted the bumper.

So you must get this checked out asap - could just be a simple sensor fault, but could be an indication of real trouble (as I found out....)

[hollywood]

if i put sports pipes on would this involve removing that cats and solve this problem?

[chrisx666]

A sports exhaust would fit onto the existing cats. You can remove the cats regardless of what exhaust you have by fitting cat replacement pipes (often called 'test' pipes). If the car is post July 92' it would probably fail a pukka MOT test with these on though.