360 : Catalyst Temperature Error Codes 1454 and 1449 during first miles of a cold start

Quite often while driving from a cold start, I have the "slow mode" going off, linked to a P1449 error, with or without the save mode (4 cylinders only) coming in : the P1454.

P1449 : Catalyst Temperature (Vesconivi) (bank 2)
P1454 : Catalyst Protection Active (bank 2)

Then, there are to cases:
- the Slow Mode persists and I have to stop, erase the code with a basic Wifi ELM 327 OBD interface, restart the engine and go
- the Slow Mode disapears and I can go on

On both cases, I can drive as long as I want with no other issue the whole day.

As the problem only occurs while the whole engine and exhausts is heating up, I suspect the motronic is fooled with an "out of range" value from one of the sensor compared to other sensors, but It would make sense to understand how it works not to have to replace everything :
- Coils,
- O2 sensors,
- Thermocouple
- Control Station (179278)

Note : I've swapped the left and right control station but the problem persists.

Anyone has had that issue before ?

Side question : which side is "Bank 2" ? Left or Right ?

 

Indeed, the thermocouple's ECU is called "control station" in some parts websites.
I guess removing these thermocouple and/or O2 sensors could be easy or a nightmare depending on how much they are "welded" to the exhaust.
But in both cases, I suppose I shall need to remove the main exhaust muffler to access these.

 

the 1449 (and 1445 which is the bank 1 equivalent) code is likely generated because the catalyst is going up in temperature, or maybe if the sender gives a wrong value.

In first case : why would a catalyst overheat when the engine and exhaust are still in heating phase ? Likely because of a wrong mix and that could come from a faulty o2 sensor. I admit it’s quite stretched, but it’s a possibility.

In second case, I’m surprised that such a sender could give enhanced values because of a fail. Would it not give no value at all ? Even though the Error Code list suggest to check :
- wiring
- thermocouple ECU
- thermocouple itself

But these codes doesn’t come off every time. Sometimes it’s right or left or both or none.

And when they come off, after erasing them and/or letting the car get in normal temperature, all is fine and they never appear again while driving.

 

Good idea, I just received one yesterday : I will test it on next ride !

 

It’s actually randomly on both sides, but a bit more often en bank2.

swapping the ECUs did not impact the chance on left or right Bank

 

Some measurements with a laser temperature sensor, when the SLOW DOWN warning appears, showed that the right exhaust header gets much warmer than the left, something like 360°C when the left one is "only" 250°C

At the same time, both sides catalysts are around 250°C as well, though.

So I suppose the thermocouple sensor and ECUs are not faulty after all, but this temperature difference is likely triggering the SLOW DOWN mode.

More driving tests also showed that this temp difference situation happens after 20-30' of "sporty driving" (high revs driving). If I "slow down" the rythm or if I cruise calmly, this situation never happens. Actually, when that situation happens, I need to keep driving calmly to let everything cool down. I sometime need to stop totally, let things cool down a bit, erase the fault codes and keep driving calmly.

It also appears sometimes while the engine is getting warm, 10' after a cold start and mild driving. If I Stop and lett the engine idle a bit after clearing the default codes, I can drive the whole day without problems.

My regular ODB code reader detects nothing about misfire or injection problems, it only gets the P1449 and P1454 codes.

But obviously, if one bank gets much warmer than the other during intense use, it means there is likely a combustion issue at higher revs.

When that situation happens, at idle, left and right O2 sensors read simillar values; both Sensor 1 (127, 128, 64, 138) and Sensor 2 (0,58, 0,58, 0,095, 0,86).
I haven't monitored the O2 sensors' values at higher revs though (I shall need a passenger to do that while I keep steady high RPM on freeway), maybe it will show some difference...

Any ideas ?
Is there some more tests or checks I could perform meanwhile ?

PS: spark plugs have been replaced less than 2000km ago

 

Indeed, I was surprised as well, but I made several measurements in different situations and everytime the catalysts were about the same heat as the left exhaust header.

I'm not sure what you mean there. Fuel adjustments I guess ?
I need to double check that.

I also have a friend with a professionnal AUTEL scanner, so I'll get there and try some more readings.