Codes P0432, P0422 Cat Threshold?

Hello All (96 355)
My first CEL in nearly 5yrs are these 2 (P0432 and 0422). I have been reading quite alot and maybe have mis read something so hopefully someone will be able to answer my problem with a fix
New cats(rebuilt here in Aus), New pre/post 02 sensors, New thermocouples and test Cat ecu's and all work fine. All this was done on my last major and have travelled approx 200kays.
Then yesterday after a bit of spirited driving Baammm CEL and this did not go out
Could this be a bad batch of fuel or do i just clear codes and if CEL comes on again maybe put some extensions in the post cats? please give me your thoughts
Oh almost forgot i also have code 1448 Bypass flap? vaccum leak or solinoid? and how can i test it.
TIA.

 

I can't imagine that the cats will have broken down after 200km. Anyway, I assume they are under warranty. Did you have high flow cat material installed?
I get the same messages, but my cats are gutted (hopefully not for long). I believe the ECU only illuminates the CEL for these messages after two or three drives, so it may not simply be your single spirited drive which caused the CEL (unless you stopped for petrol along the way).

For code 1448, I guess you could check the resistance of the bypass solenoid (55ohms). Also see if there is voltage present on the harness connector (green-black wire) with the igntion ON (and I guess with the immobiliser OFF). It's the solenoid which doesn't have the blue plug on it in the extreme right hand corner of the engine bay. Try to trace the vacuum line from the solenoid to the bypass valve actuator to see if it is ok. I would focus on the bypass valve problem first as OEM bypass valve solenoid failure usually leaves the valve closed, leading to high temperatures.

Anyway, it's good to hear your car is up and running, even if you are getting these messages.

 

Thanks Ian. Yes mate high flow. Would you believe that the new Crank angle sensor I installed was. .015" shorter than the one removed putting just outside the maximum air gap distance. Pays to measure things I suppose. I will check the things you listed cheers and thanks again.

 

Just another thought, Paul. Can you actually hear the bypass valve opening at high rpms? If you're not sure, I did read a message on the forum which mentioned attaching a camera/iPhone with zip ties facing the bypass valve. Might be a risky technique though. I don't know how these devices cope with high temperatures.

If the valve is actually working, then maybe the bypass valve temperature sensor or temperature ECU/TCU is sending erroneous/fault signals to the ECU? The bypass TCU should be interchangeable with the cat TCUs, so it will be useful for faultfinding. If you reset your ECU messages, interchange the temperature TCUs and do a couple of test runs, the ECU messages might change.

An excellent find. I think you owe the guy who thought of this a case of beer

 

My bypass thermocouple is tied to the rear panel the exhaust is aftermarket. I have a spare TCU. Im wondering could I video the valve actuation stationary or does the car need to be under load?. I checked all the solenoids and vacuum lines today as well as vacuum tested the valve and everything is great. No leaks and has power at solenoid. I have cleared codes and placed the spacers in the post O2 sensors but need to test drive

 

I'll let the experts answer this, but I seem to recall reading it has to be under load (similar to a turbo charger). Sounds like a good excuse for another couple of test runs. I guess you don't have to use the latest and greatest iPhone/Samsung for the video tests. Does someone in the family have an unwanted ipod with a camera?

 

Seems to be fixed. spacers in Post 02 sensors and made up 3 of the test pipe TCU box's some time ago. Installed one of them for the Bypass thermocouple and so far NO CEL Glad there were no constabulary about could have been a hooning moment which may not have been easy to explain

 

Do the test pipe TCUs ignore temperature, create a fixed false temperature or set a higher/lower temperature for SD (Slow Down) lights? If you still have cats (high flow or otherwise), you still need some kind of temperature warning.

I still don't fully understand the control of the bypass valve on the 5.2. The 5.2 manual says:

On the US [and Australian] version, the by-pass valve operation is controlled by the ECU, through a third thermocouple detecting the temperature downstream of the valve. The temperature increase, caused by the exhaust gases, informs the Motronic ECU about the performed valve opening (through the thermocouple and the relevant ECU [TCU]).

The manual uses the words "controlled by", but the text suggests the TCU is only for position feedback. Is the valve still controlled by other parameters, such as rpms and gear selection?

If you fit a test pipe TCU to the bypass valve, will it tell the Motronics ECU that the valve is closed all the time, open all the time or something else?

You could literally be playing with fire here. I look forward to seeing the results of your next drive

 

They set a particular voltage so the SDL dosen't come on (Personally not real keen on that idea fire fire fire). From my understanding the ECU controls the bypass valve providing it has a good vaccum source. If for instance there is a very high temp from the themocouple the valve would be opened. Apparently when you fit an aftermarket exhaust there is no place for the thermocouple and not required hence the reason mine was cable tied to the inside of the rear panel near the tail light(Very common practice apparently??). Some cars can give a CEL due to no temp change or ambient temp I'm unsure so i have 3 box's i made set at 1.5 volt output (Mid way). I will be disconnecting it after a little while and change the TCU with the spare i have and see if the code P1448 comes back. I made up a test harness and used a propane torch to heat the thermocouple and all 3 checked out spot on with various thermocouples !But! the bypass TCU is the original Black composite type and are prone to malfunction which may have happened on my last drive so i will test it again over the weekend. Valve is definitley working though and my cruise temp/traffic temp are very consistent. I'm going to play around a little because i do believe fuel grades/quality could certainly have some emphasis but i could be wrong. Hopefully someone might chime in and offer some real knowledge from their own experience mate

 

Ian
From the OP that made the box's and was good enough to show his drawings/diagrams he actually modified one box to send the same voltage signal to the ecu for both thermocouple's (For the rear right hand side) and then just a single signal box for the LH side. Check out Thanks Gothspeed thread in this section seems he has a similar box doing the same thing as mine

 

Paul, I made something similar for my car using a design by Kiwi FChatter "wbt". It simulates a constant normal temperature.

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

However, my cats are gutted, so I don't have to worry about cat temperatures (neither do people with test pipes). You have new cats, so, at some point in the future you will need to find a different solution. Normal TCUs identify high temperatures (caused by cat failures).

 

I haven't faked that side of the system mate. All pre and post cat O2 sensors and Thermocouples and TCU'S are connected. I will however need to adjust the TCU bypass voltage back to. .5 volt from 1.5volts

 

One quick question.

What temperature is your car running at?

The reason I ask is, if it runs too cool (not getting up over full operating temp of 176ºF) it wont get out of the secondary fuel enrichment. The extra fuel can cause the cats to run hot. So check your coolant temp and if needed you may want to replace the thermostat.

 

Ah.. so you have an adjustment on your custom TCUs? Then I don't really understand how they work. I just assumed your custom test pipe cat TCUs ignored the thermocouple signals and just had something inside them which replicated "my" resistor and diode plug.

 

No CEL or SDL between voltage. .5 and 1.5volt supply to ecu from TCU.
I used/made the faking boxes from.a OP. !Jevs!
Ernie when your on the open Rd I see approx 70C and in traffic approx 90C
Never had temp problems

 

Sorry, I'm not familiar with this type.

I just need to know if you understand the risks of using faking boxes. If there is a permanent simulated signal (between 0.5~1.5v), then you won't get an SDL and run the risk of damaging the engine/exhaust in the future. From what I've read, the cat material can break down and clog up your exhaust. The resultant temperature increase is normally identified by the SD light/s.

If you're putting a fake TCU on the bypass system, how does the car know if the bypass valve is really open (or closed). Does a fake Bypass TCU tell the ECU that the valve is permanently open or permanently closed? If the ECU sees a permanently closed signal, will it limit engine performance for safety reasons?

 

Yes I understand that. I'm not using fake boxes for the post 02 TCU'S they are connected so SDL is still functioning.
I do however have a fake box on the bypass which the ecu doesn't respond to if it sees .5 volts as the bypass function is controlled by the ecu at that voltage so engine demand or load the way I understand it. If I'm wrong I will no soon enough!!

 

On my 5.2 i need extension or else I used to get a cel abbout every 10 drives. 1999 gtb f1

 

Do you have high flow cats, Grant? If so, which manufacturer? I may need to install extenders when I fit some new Larini high flow cats to my '98 5.2.

 

I'm interested as well Grant. I have just installed the extenders to the post 02 sensors as my car has high flow cats there quite short really . I have the "L" shape ones also but I like a bit of trial and error so I know what works for sure. In saying that if it don't work well it's back to CEL light.

 

I have hyperflows but they are the same as ?? Cant remember

 

Mine are the minicat extenders and they are straight and 7 years old likely.

 

Just buy extenders, for 5 years I fought cel because the system is very sensitive and monitors all the time.
I also used to have to buy new o2 sensors every 2 years. I now have had the same ones for over 5.

 

My guess is by moving the sensor out just that 1.5 inches it has also helped increase its life substantially

 

I can recommend mini cats to reduce / eliminate these errors.