Peugeot gearbox adaptation help

[vilmoscica]

Hi, all!
We had the automatic gearbox and the torque converter changed in a Peugeot 407 SW, and currently trying to finish the adaptation process.

However after the adaptation was initiated and we went for a test drive after a few hundred meters we got a P0734 error message.
Is this normal during the adaptation process?

Thank you for your input!

[xantia_v6]

Was the gearbox replaced with an identical (same part number) unit to the original?

That code can be caused if the replacement transmission has different gear ratios that don't match the ratios programmed in the transmission ECU and maybe the engine ECU.

[vilmoscica]

Yes, the part numbers match.

If the gear ratios are different, will going through with the adaptation process solve that?

We kind of freaked out when the error popped up ( it was plugged in to the diagbox during the test drive) and went back to the garage.
After we killed the engine, reignited and and ran another scan there were no faults found.

So maybe we should just push through and give it some time and mileage to synchronize?

[xantia_v6]

No, the values are hard-coded into the ECU(s), and cannot be changed with adaptation or a diagnostic tool. A specialist may be able to recode the firmware, but I haven't heard of it being done.

If the replacement transmission really has the same PSA part number then it should have the same ratios.

[vilmoscica]

I understand, thank you for elaborating!
We made sure to get a replacement part with the same part number so hopefully there is some other, less serious reason for the fault message.
We'll keep on digging.