Hi
I have an issue which seems to be reoccurring on seat ibiza cupra 1.8t (mk3)
they run a 512k me7 ecu.. narrowband controlled, dbw, non vvt

I am seeing more than a couple of repeat issues on these, which I cant fathom.
The lambda control, which is only functioning on idle and cruise, throws a "malfunction in circuit" code, and the voltage viewed via vagcom on block 031 drops to zero's and the fueling adaption  then jumps to +25% enrichment, often causing stalling etc, and on the remapped cars with bigger injectors/MAF etc, nasty black smoke and off scale afr's

the lambda probe is not the issue, its been replaced a few times with original sensors, rewired back to ecu, ecu earths rewired, all to no avail.
An interesting phenomena on one of these was the 2nd O2 sensor sits with normal switching voltage fine right up until the moment you plug in the B1S1 controlling lambda and then they both drop to zero volts on 031 block and it does its +25% lambda adjust thing.

Anyone here got any bright ideas?
I am out of them here.
Only fix, which was'nt a fix, was to discinnect the b1s1 lambda and the cars run perfectly.

any help welcomed.
tia

I'm experiencing similar phenomena (dtc + weird o2 behaviour). Haven't found the cause of it yet