355 Few codes, headache

I just ordered a couple of precat sensors from this USA site:

https://cars245.com/en/item/bosch-0258003819-lambda-sensor/

I'll check the heater resistances when they arrive.

The webpage also references this:

https://cars245.com/en/item/bosch-0258986507-lambda-sensor/

Perhaps for those who need to adjust the length of their leads.

 

are those a straight swap plug and play?

I’ve read some need cutting and mending

 

Not sure, but if too long, you could always fold and zip tie the excess. The strange thing is, I don't see my extension pieces in the parts catalogue. I'm not sure if they are standard.

 

Ok.

LH pre cat (blue tape) = 3.8
LH post cat = 2.6

RH pre cat = 3.6
RH post cat = nothing/open circuit

so just to confirm

post cat sensors are Bosch 0258003820?
Pre cat sensors are Bosch 0258003819?

 

Also, looking at my codes.

replacing all the Cat ecus, and if required the thermocouples I’d like to see the codes 1449, 1454 disappear.

the faulty bank 1 post cat 02 sensor being replaced should hopefully cure codes 1117, 0140.

@Qavion

you said “
Feedback to the ECU about heater status is also done in sensor pairs (precat sensors is one pair, postcat sensors is another pair).”

so my take from that is that the bank 1 post 02 sensor being broke could be causing the 1121 code (Bank 2 downstream ) to appear also?

 

Post 22.....

 

ah yes thanks

 

I corrected myself…

So the ECU seems to control heater current in pairs. If one sensor is open circuit, I don’t know how it would properly control the current going to a single heater.

(EDIT) Apart from the open circuit value, these values are similar to mine. This sounds good.

How many miles on the clock do you have. All the O2 sensors may be original and probably need replacing anyway.

I don’t know. The codes are for a 360. In theory, on the 355, the ECU is not able to tell from the heater wiring if individual sensor heat is malfunctioning. Watson thinks that code 1121 is actually for a crank sensor. It is on the 2.7 car, but I can’t be sure on a 5.2. I recall that on Ferrari 348’s, 1121 can be generated simply because the car is not running, but I haven’t seen this code on my car with the engine not running. Also, the 5.2 only has one crank sensor, so any fault is going to affect both banks. A completely failed crank sensor will stop the one and only fuel pump operating.

 

I mean replacing them for sensing reasons, rather than heater failures. If you’re going to lift the car in the air and take off the underbody panels, it’s probably a good idea to change all the O2 sensors.

It was noted a few years ago that Bosch sensors were having quality control issues. Some precat sensors were found to have post cat tips (i.e. They had small holes instead of slits). Make sure that yours are ok before fitting them (visually and with an ohmmeter)

 

The car has 70,000 miles, I usually use the car most days although this past year has been an anomaly whilst I was having my garage at home extended, so I couldn’t use the car much.

My plan was to change the RH post cat oxygen sensor along with the Cat ECU’s, see how the car responds in terms of codes, and then change the other oxygen sensors when I can access them easier when the rear ends stripped, although if you feel I should really replace them all at the same time I’ll do that instead?
As I mentioned previously I’m replacing the clutch and whilst at it the starter motor as I have an intermittent starting issue where I can hear the solenoid click but not fire!

thanks for the heads up with the new sensors, will check when I receive them, and also thanks to everyone else for taking the time to assist me with this issue, very much appreciate every post.

 

Whatever is easiest for you. I assumed the post cat sensors were hardest to access, but I haven't checked recently whether you go from the top or the bottom (or have to do something silly, like go through the wheel arches).

You can buy refurbishing kits for the starter, but it may be worth buying a relay if you have a starter relay fitted to your car. Mine is located adjacent to the footwell relay panel. If the relay contacts are pitted, they may not be providing full current to the starter.

Here's my LHD relay panel. I assume the starter relay will be on the opposite side on your car.

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LHD panel here (ignore the red circle)

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Yes I have that, appears to be a Ford relay?

When the issue occurs a tap on the starter with a bar will usually do it, does this rule out the relay, or is it a possibility the relay doesn’t provide enough current so the starter gets stuck?
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Don't know. It's easier to change the relay than it is to refurbish the starter as part of faultfinding, but the relay is probably relatively new.

According to this ad, the Ford relay is 70 amps! Not sure what mine is.

https://www.ebay.com.au/itm/196409805171?chn=ps&_ul=AU&mkevt=1&mkcid=28&google_free_listing_action=view_item&srsltid=AfmBOoqf0M6JhbX7cFOXWW9dnRh4dq8R9gWFDFk1VqStSM6l94c26TZEHpk&gQT=2

 

So I’ve just replaced the 3 cat ecus, started engine and the slow down light is still flashing.

I then replaced the 2 thermocouples and still the light is flashing.

Do I need to do the disconnect battery and reset main ecu?

I’d have thought the light would have gone off instantly, I’m not able to drive as the rain is terrible

 

I'm not sure which faults are latched, but a battery reset should clear all faults. Did you make sure the ECUs were attached to the correct thermocouples and the correct ECU connectors?
I'm not sure if a faulty thermocouple probe for the bypass valve can trigger a CEL immediately. Did the SD light come on as soon as you started the engine?

Just noticed, you have too many relays and fuses for a 5.2 model. Do you have a fuse/relay guide on the relay panel cover?

 

I removed and replaced the ECU’s one at a time, so no way I could have mixed them up, unless they were already mixed up to begin with.

What exactly could be mixed up?

Also I only bought 2 thermocouples, I didn’t realise the 3rd ECU had one too! I’ve replaced the one for the left Cat and the one for the right cat

Yes the Slowdown light is flashing as soon as I start the engine,

 

Sorry, I've forgotten the history of the car. Did the CEL appear out of the blue or did things start going astray after a major service or from when you bought the car?

As mentioned elsewhere, the wiring going from the Cat ECUs to the Motronic ECU has specific colours. The Cat ECU plugs behind the rear bumper are close to each other and could get mixed up, but as long as the wiring going to that Cat ECU also matches the respective thermocouple, it should be ok. e.g. bypass ECU thermocouple should have a Cat ECU which has purple wire with black stripe (in the harness going to the Motronic ECU). If you can't determine colours, then you'll have to do resistance checks between the Motronic ECU and the Cat ECU wiring.

Of course, there may be other issues, such as wiring faults. It may pay to do resistance, earth and voltage checks anyway (on all three Cat ECUs).

Wiring diagram here:

https://www.dropbox.com/t/A8LurEitnBvdzHtC

 

I have both a CEL and SDL, a previous owner removed the bulbs, but it’s worth noting I’ve had the car 6 years and it’s been fine up until this latest issue.

the CEL goes out now but that’s because I’ve cleared the codes, what isn’t going out is the flashing slow down light as soon as I start the car, I’m going into limp mode after 10-20 minutes.

Regarding the 2 ecus behind the rear wheel, could I not simply swap the cables about and see if the light went off then?

for now, I’ll leave the battery disconnected overnight and see what happens when I get home form work tommorow, will be a sleepless night I’m sure as I really hoped replacing the ecus and 2 thermocouples would have fixed it.

the probe for the bypass valve, so that would cause a CEL and not a SDL if the probe was faulty?

 

Yes. Either the two pin plugs (braided EGT harness) or the 4 pin plugs (but not both types). Repeat the battery reset.

 

My memory fails me on this one. I don't know if the car has to get up to temperature and/or over the rpm threshold for bypass valve operation to trigger either or both lights. Looking back through the forum, you get all kinds of answers.

 

If the bypass valve thermocouple is faulty then hopefully one of the two thermocouples I just removed will be ok, I’d have to swap them about, it would be extremely unfortunate for me if all 3 of my old ECU’s and both the old thermocouples I removed were all faulty.

If I’m not mistaken these 3 codes relate to the ECUs

P1145 = Pass side CAT ECU
P1449 = Drivers side CAT ECU
P1448 = By Pass Valve

I’ve just done a code read, but please bare in mind haven’t driven the car so it’s only for reference

P1449
P1447
P1691
P1452

I cleared the codes before I installed the new ECU’s and thermocouples, so I’m surprised to see P1449

 

This is quite baffling. There may be a wiring issue. I'm assuming you didn't turn on the ignition with any of the RH components disconnected?

I don't have a code descriptions for these.

The code description for this one is pretty vague... Signal max/min. I don't know if this is purely an ECU issue. The faultfinding chart says: check wiring, check valve, check vacuum leakage. Since the code descriptions are taken from the 360 which has two bypass valves and uses vacuum to keep the valves closed, I don't know how much of the faultfinding is relevant. Can you say that the bypass valve has been operating? Is there a distinct increase in sound when you're driving "enthusiastically". Has anyone hooked up the vacuum lines so that the bypass valve is always open?

 

Gentlemen,

May I suggest you focus on one error code at a time. 1449 is a good one to look.

Put a DVM on the output of the TCU to the car ECU. What sigal do you see when you turn on the car?
It should be less than 1V. Do you see the same at the car ECU 88 pit connector?

 

Maybe you should have ordered a "no cat dummy" from Technistrada. They are useful for faultfinding, and simulate a normal cat temperature. That eliminates the cat, the cat thermocouple and cat ECU from the list of possible faults, leaving only the wiring and Motronic ECU as possible faults. You can make your own with a diode and resistor if you're electronically inclined.

https://www.ferrarichat.com/forum/threads/simple-2-7-slow-down-ecu-replacement-only-for-no-cats.538719/