430 What are the odds that both my Thermocouplers are bad

I noticed something odd. When I clear codes and start the car stone cold in about 10 seconds it will flash the red slow down light and shut down. Right after if I star the car it will be fine. My car's always been like this and did not think anything of it until I got a more advanced scan tool. The codes it is throwing are cat related and one of them actually points to cat protection mode activated. I read EGT with the tool which shows -25 fully warmed up. I understand why the car is shutting down. It shuts each bank down due to it thinks the cat temp is way too hot and is protecting them. I have the codes on both banks. I was super careful when I put the headers on with the thermocouplers. Did I likely just damage both? Or will just one bad one wreak havoc.

 

Was your Slow Down light triggering when the car was completely cold?

This is intersting although I have a 430, the donts(gaskets) mentioned are toast. I can see them flaking and parts actually missing. I thought that there was a very tight seal there regardless, but I obviously must be wrong.

My issue that leads me to believe the thermos are done is that 10 seonds up on start up the slowdown light triggers and shuts the car down as both banks I believe have damaged thermos. When restarting the car it is runs but throws the car codes one of which says protection mode activated. At that point I believe the car is running off default settings.

 

For clarification I did hook up my scanner (LaunchX431) and was returning these codes. This is why I thought the thermos had to be shot as it threw the codes when the car is completely cold. That was the only logical thing I could surmise. The codes are the same for both banks. When the car is restarted it is in the protection mode I assume that is why it starts and drives fine. The P0340 is due to the headers but the other two I assume have to be caused by a bad thermo.

p0438 Left hand temp sensor high inpug,
p1454 - Protection Activation for LH Cat,
p0340 - Cat below effeciency Threshold

 

I should have made it more clear. I can clear the codes and adaptions via scanner or completely kill the power to the car and let sit a day. When doing this there should not be any stored codes. With out fail every time I start the car after completely clearing the codes it will shut off in about 15 aseconds and register the above codes. When I then restart the car it starts and runs but is in the p1454 - Protection Activation for LH Cat code on both banks. I can drive the car fine. If I kill power after this and clear codes I can replicate this scenario with out fail.

430 does not have cat ECU so that is eliminated by default which leaves me with the thermos. I am fairly certain this is the issue. Even when trying to read EGT when the cars warm it says -25.

Hopefully that clears things up a bit. I am a bit of a rambler...lol.

 

I think the thermocouplers are very sensitive as it relates to the wiring due the extreme heat. I don't have anyone I can swap with. I was curious what would happen and how the car would behave if I just disconnected them. If it does the same thing its doing and there is no change I can reason that they are dysfuntional.

 

My reasoning is that both were damaged when removed to install headers. This seems common as the wires become very brittle and sensitive with the extreme heat they are subject too. It is really the only thing it would think can cause slow downn when car is cold. We shall see.

 

It is a 430 there are no CCU's. I do think the thermos are done and registering a high temp, shutting both banks done as both thermos are bad. This turns the car off effectively. Fix is to delete thermos with tuning or get new ones.

 

Interesting I will try and cross reference parts for thermo. If anyone knows the cheaper Bosch alternative I am all ears.

 

That is interesting. I don't see the 430 listed, but the 360 and 430 are the same from what I know. Is there anyone that is actually running these. Price is right, but I am skeptical. Those things are basically living in Hell's inferno and live a rough life. I wonder how long or if these would even work.