Check engine right after major service, HELP

Hi all,
Just picked up my 550 Maranello today. Had the 45k major service done.

I drove it 50 miles back to my house and the second I'm on local roads, the check engine light goes on.

I pop the hood thinking something must have jiggered loose, and sure enough there is a blue plug right next to an empty outlet (in front of the driver side firewall). So, I plug it in, turn on the car and the check engine light is still on.

What do I do? Was the plug the problem, was it suppose to be unplugged? I'm really hoping the system sensed the plug becoming dislodged and needs to be reset to remove the check engine light.

Knowledge/ advice on this issue would be appreciated. See pictures for details (check engine light, the plug unplugged and then after i plugged it back in).
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Are these suppose to be unplugged? If not, I assume this would cause a check engine light.

Can someone please confirm?

 

If I was you, I'll take the car back to where you had the service done.... Let them fix the problem...

 

The box you plugged the harness back into is a "slow down ECU" - also called a "cat temp ECU". Indeed, if your car doesn't have any exhaust modifications, it should remain connected.

I don't recognize (from your photo) odd butt-connector wiring that appears to be spliced from/to that harness itself.

 

That module that the blue plug connects to is the catalytic converter temperature "ECU", and it's part of a safety system that shuts down 1/2 of the engine if its cat converter is overheating.

The blue plug is the signal from the "Cat ECU" to the main Motronic ECU, and it should never be disconnected, and it will definitely set a CEL if it is. FYI the yellow plug is the very low level signal coming from a thermocouple in the exhaust, just downstream of the cat converter. It should also never be disconnected.

The CEL is a "hard" fault, and it will not clear itself. You'll need an OBD2 reader or SD2 to clear it. Once cleared, it should not return, unless there are other faults in the system.

Black Horse is correct - you should bring the car back to the people who performed the major and point out to them that this plug was disconnected, and get them to clear the CEL and run a scan for any other codes or issues.

p.s. Daniel makes a good point. It's possible someone has tried to bypass the cat ECU or its function. Definitely get an OBD or SD2 scan of the system and ask some questions of the folks that did your major. Also, FYI, there is an identical module on the passenger side. Check to see if its blue plug is disconnected - that will give more clues what is going on.

 

All on the right track, I'm taking the car back to the place that services it for one last fix, this'll definitely be on their list of to-dos.

Also, last night I was reading up and read about how this was for the cat... I also read that tubistyle exhaust delete the cat. I found out recently that my car has tubi, so there lies the plug issue.

Which bring me back to the bigger question, why the check engine light. And when I bring the car back, it's to a place about 40 miles away. Oil pressure, temp, water temp and all gauges appear to be normal, minimal risk at driving it back to this place?

-Michael

 

Yeah, I noticed that. On both sides of the car there are small black boxes spliced in that have on/off switches. Any thought as to what they go to?

 

So... I failed emissions and the read out showed misfires on 1, 2 and 3, r"andom/multiple cylinder misfires detected" and an "air intake temperature sensor 1 circuit low".

Any thoughts or is this just a job for the guys who did the major service? The car runs fine.

 

Most owners opt for only the Tubi mufflers (cans) at the rear. Are you SURE you're catless?

The random misfires could be due to the ignition system, or non-synchronised throttles. I've seen both.

You would think that non-synced throttles would not produce misfire codes, but that's the charm of Ferrari and Bosch trying to comply with their first generation OBD2 ECU's......

 

No, I'm not sure the cats are removed. I'm just assuming they are because both sides were unplugged and I read tubistyle installation could remove the cats and still keep the car ok for emissions.

I was gonna say, the engine performs nicely and doesn't appear to have an issue. Interesting to know if may from the relationship between Bosch and Ferrari components.

Is there anything I can do to check if it's the non-synced throttle, also, where can I look to see if I still have cats.

2 side questions: my radio isn't turning on (no sign of life). I checked the 7.5 fuse for "instruments" but didn't see anything out of the ordinary. Thoughts? Suggestions?

Also, this one is kinda stupid, how do you lock the 550 Maranello? Every time I do so, 15 seconds later the alarm goes off. Been having to manually lock the doors.

Sorry for all the questions, guess I'm becoming an owner by fire.

Best,

Michael



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The cats are hard to miss, but if you don't have anything to compare to, it's understandable that you might not recognise them. They're connected directly to the exhaust manifolds on both sides of the engine.

Here's an illustration from the Ricambi website that shows the cats (Items 2 & 3):

https://www.ricambiamerica.com/media/catalog/category/550_22.jpg

If both blue plugs are unplugged, a previous owner has managed to bypass the cat ECU's, which is a very unwise thing to do on a car that still has cats.

If the cats are indeed gone, then there's not much sense in keeping the cat ECU's but they have to be bypassed, not just unplugged. The bypassing could be that additional wiring that Daniel commented on.


Concerning the throttle sync, you'll need a good OBD2 setup, a Galileo, or an SD-2 to check the TPS and MAF sensor outputs and balance them. It's not a procedure for the faint of heart.....

 

I'll try to get a better look under the car and see if it has cats, I couldn't see anything at first glance.

It sounds like I need to take it back to the shop (they also did my pre-purchase inspection), so hopefully they'll fix the issue


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To start with, the cat ECU's in your picture have black 'potting' which immediately suggests they're quite old, and likely cooked. For a long time (maybe since 2004?) these have been manufactured with a newer, more heat resistant green sealant. So, whatever the ad hoc wiring is, it masks either an actual need to replace the cat ECU boxes, or is some kind of wizardry because of your modified exhaust.

Additionally, if there's an 'on/off' switch in the spliced wiring, I'd certainly like to see a picture of it. The Gothspeed cat ECU (https://www.ricambiamerica.com/gs179278-catalyst-temp-ecu-simulator.html) does something similar, but is an integrated design. My "spidey-sense" tells me that switch was installed by (1) somebody who didn't want to install proper new Cat ECU's, or (2) somebody who modified the exhaust (cats) and couldn't resolve a thermocouple/cat ECU issue.

I doubt the spliced wiring goes to a flux capacitor; those were only installed in the 575 models. But just in case, don't exceed 88mph until you know for sure...

 

Ok, so I'm super confused. You see the cat in the picture I took? All I see is the fire wall (the silvery thing in the back). So, Where exactly is the cat in my picture?

Here are pictures of the boxes, they look like early/ more primitive version of what gothspeed has.

In any case is this hurting the car? Hurting performance?

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The catalytic converter is *NOT* shown in your picture. Your picture shows the Cat ECU (160454) and some custom thingy.

Is it hurting performance? I dunno. Cars are not supposed to run with warning lights on, whether it is a Ford or a Ferrari. Take it back to the shop that did the service, and get them to explain, repair, or remediate.
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Of course the warning lights can't be good. I just meant if the cat ECU is bypassed, what in theory would that do to performance.

Yeah, bottom line the shop that did the pre-purchase and my major service are gonna have to take care of this/ give me an explanation. I might try to contact one of the previous owners, see if they can shed some light on the issue too.


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The Cat ECU and its thermocouple are simply a safety system to shut down one bank of the engine if the exhaust temperature out of the cat for that bank is too high (usually indicating there is fuel being combusted in the cat, instead of the engine due to ignition failure)

AFAIK this system doesn't tell the Motronic to adjust fuel or timing, so it has no effect on performance if everything is running as it should.

 

To the OP, this system is a critical safety system. If you don't want your car to catch on fire, the CAT ECUs need to be functioning properly. If you get a SLOW DOWN light triggered by the CAT ECUs, you can't ignore it. CAT ECUs are relatively cheap also.

We've all been there with CELs and SLOW DOWN lights. If the mechanic knows what he is doing, he can sort this out. Hang in there.

 

What has been written above by other posters is correct. I will add that CribbJ and I contributed to a thread I started years ago about the SDECU (slow down ecu in your pictures). I think several others have taken that work and took off in other directions with that as a base. Perhaps the most important take away from that thread is that you can apply 1.5V to the SDECU wiring and keep the SLOWDOWN LIGHTS off. It appears that the aftermarket boxes shown might do that. Open the box and see if there is a 1.5V battery in there. If yes that is your answer. That for sure would be a bypass of the SDECU sytem. If no battery is in there then you will have to measure the output of the boxes and that will tell you what the previous owner was trying to do. The CHECK ENGINE LIGHT is for specific stuff like the misfires seen via the obd2 port as p0300 series codes. The SDECU triggered the SLOWDOWN LIGHT not the Check engine light. That is what I remember. I have not messed with this system in quite some time so memory is foggy. I think your identification of the unplugged plugs was just coincidental in that you have now coincidentally found bypassed SDECU's.

Ferrari uses the SDECU to watch over the motor because the motor acts like 2 6 cylinder motors that do not talk to each other. So you don't want 1 side running good and the the other side not dumping gas into the cats and causing a 1 sided meltdown. If your cats are gone you can bypass the SDECU. If your cats are in place then you need a way to monitor engine function. That means your option is to restore the Ferrari SDECU system or bypass with 1.5V to the SDECUwiring + monitor with manual Exhaust gas temp probes (which I have done), or see that thread I'm talking about and get the aero?? exhaust gas monitor CribbJ speced out, or search the posts of drbob1 who found a cheap aftermarket SDECU that has some minor issues but works cheaply and reliably. I hate the Ferrari SDECU's they are a retirement fund for Ferrari. They always break.

It is possible that Ricambi America has a replacement SDECU from Gothspeed or a bypass box from Gothspeed. I'm not up on what he has made for this issue. But I know Goth personally and his stuff works!

Hope that helps...

 

Thanks, that helps a lot. Checking for the batteries now.

Also, to add to the drama, I found an air temperature sensor unplugged.

Taking in all this information, also bringing the car back to the shop next weekend and bought an OBD2 from BlueDriver.

I'll keep everyone posted regarding the results and recommendations.

All of it has been greatly appreciated.


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I realize that I am criticizing someone else's work here and that generally that is poor form, but I would take it back to this shop, have them fix it to your satisfaction, and then never use them again.

Absolutely unacceptable for this car to be handed back to you with so many issues (unplugged connectors, nonfunctional radio, etc).

 

At this point, I would question everything that was done.

 

Lets not go on a witch hunt yet people. Yes the garage seems to have failed plug in an air sensor which can happen and to me sounds like the most likely cause of the issue. The others were probably disconnected when they got it and they left them like that which makes some sense (even though I would consider consulting the customer about that as better practice).
The radio not tuning on, the battery was probably disconnected during the service and the radio needs a reset of some kind or a different way to turn it on relative to normal.